No. The effect of a cooler sun is smaller than the increased forcing from higher levels of greenhouse gases. http://www.realclimate.org/index.php/archives/2016/11/record-heat-despite-a-cold-sun/

We know for sure that climate change is not caused by changes in the sun because there have been no long-term trend in the solar behavior that can explain the global warming. http://www.realclimate.org/index.php/archives/2012/12/a-review-of-cosmic-rays-and-climate-a-cluttered-story-of-little-success/

False. CO2 disrupts the planetary energy balance.

The Antarctic ice sheet is losing mass: https://www.nature.com/articles/s41586-018-0179-y

The best indicator is the global sea level, which does not show the same degree of fluctuations as it reflect the integrated heat content on the earth. The fluctuations in the temperature record is partly due to the distribution of thermometers which do not cover the earth completely and evenly. Furthermore, there is no force from the Little Ice Age that pushed the current temperature, but a present energy imbalance due to well-known physical conditions. We have advanced instruments that measure every physical aspect that can influence the atmosphere and the oceans, and there is one smoking gun: rising CO2 and other greenhouse gases.

This statement is does not appreciate our current understanding. To understand this, one needs to model the climate and how the it matters for the atmospheric circulation and the planetary energy balance. In some regions, it gets drier (typically the subtropics) and in others there is increasing precipitation (typically the mid-latitudes). There are some indications that the rain on a global scale is getting more intense and concentrated over a diminishing area: http://iopscience.iop.org/article/10.1088/1748-9326/aab375

The claim is false: the graph shows a misguided comparison between (1) the average of climate model simulations for a part of the upper atmosphere that is strongly affected by the clouds and the Hadley cell in the Tropics, (2) temperature derived from satellite measurements, and (3) balloon data. This exercise fails on statstical terms, since the comparison should be carried out between all individual climate models (to show the their spread) - one cannot expect the average value to match the one that is measured, just as one does not expect that the temperature in Washington always to be the same as the mean temperature in Washington. There are also issues with using the satellite data as a reference, since satellites do not measure temperature directly. They measure light and make use of algorithms based on the same principles, as those used in the climate models, to estimate the temperatures. Hence, the satellite data are also model results, and the comparison between the two is like comparing different models. The satellite data data have some issues regarding how different records are stitched together from different missions and how the signal is affected by clouds and other factors. The balloon (radiosondes) do not give a good representation over the upper air, as there are few of them. More information at http://www.realclimate.org/index.php/archives/2016/05/comparing-models-to-the-satellite-datasets/

The important point is that the net effect to the CO2 exchanged between different parts leads to a rise in the CO2-concentration, which now has passed 400ppm. There is no doubt that the increase in the concentration is due to burning of fossil fuels - it's easy to calculate based on the amount of oil, gas and coal that is burned and the chemistry. A comparison between the sizes of the various fluxes between the different parts clutters the discussion. Furthermore, water vapour (H2O) has a short life time in the atmosphere compared to CO2. It rains out after a few days whereas CO2-levels stay for centuries.

Even if melting of ice does not say what is causing the warming, we can eliminate a lot of candidates. The earth has never been monitored as closely as today and with as accurate instruments - ranging from thermometers on the ground to satellites above. We can measure any physical condition that can physically influence the atmosphere, and then rule out the factors that are not present. The climate has always changes, and there has always been a physical cause for that: be it changes in the Earth's orbit around the sun, changes in the ocean currents, volcanoes or changes in the sun. The fact that past variations in climate have been so pronounced suggests that the climate is sensitive to changing factors, such as increased levels of CO2. This is bad news. Increasing CO2-levels is a smoking gun: the greenhouse gas properties CO2 is well documented - it is measured in the labs and explained though quantum physics.

The greenhouse effect exists on other planets in the solar system and explains why planets like Venus has such a hot surface. The big picture is explained in the paper 'A mental picture of the greenhouse effect' (https://bit.ly/2PQ4wz3), which also presents some empirical evidence contrary to the false statement in the video. The challenge, rather, would be to explain why increased levels of greenhouse gases potentially would not influence the greenhouse effect (it does).

Indeed, and anyone is free to publish their findings on the Internet (and people do).

I would explain this differently: they give the curve so much freedom that it conveniently matches the data by allowing for a large number of coefficients in the equation describing it, but these coefficients do not have a physical meaning.

This is baseless and not science.

The former is Melankovitch cycles where Jupiters gravity affects the orbit of the earth, but the latter is a mere speculation.

This is claim has never been proven, and there is no indication that this is true. Scholars have looked for a long time and never found any indication. Nor is is possible to explain how the physical connection could work. The moon and sun affect tides in the ocean, and has some local oceanographic effects, but this cannot be extended to global warming or cooling,

No. The film was way too unrealistic.

This is completely baseless. Probably, this claim is based on one single "mad scientist" with that view, but does not reflect the sentiment of the scientific community.

This is not based on substantial facts, but such claims of "cycles" is pure speculation. The data records are not long enough to establish the existence for such long cycles, and they claims are based on curve-fitting exercises.

This misrepresents the position of the Danish Meteorological Institute (DMI). The text is misleading.

This is a misrepresentation of the facts

This is false and contradicts the observational data. There are new scientific publications now which independently indicate that there never was any "pause". The best indicator is the global mean sea level which has suggested an increase ell the time,

This is false when it comes to the global mean temperature. There may be some cooler locations, but to use that is misleading.

This is misleading. Even if there are some single locations in the Arctic with 2m thick sea ice, it is not true for the Arctic in genera. In fact, the NISCD indicates that the thickness is thinner now than before. Hence, this is a false statement for the entire Arctic.

This is false. See the data at NISDC.org). THe Arctic Sea Ice extent is lower than ever observed.

This is misleading, as the Arctic has been exceptionally warm the recent winters. The 2016 December mean temperature for Longyerbyen/Svalbard was -6C. However, the temperature varies from place to place and from day to day. It is typically below 20C in somewhere in the Arctic for some days, but the general picture is that the Arctic is worming up strongly. This is documented in an upcoming report from the Artic Monitoring and Assessment Programme (AMAP.no) called Adaptive Actions for a Changing Arctic (AACA).

The science is not settled, as there is still research ongoing - what consequences will the global warming have? The question whether the earth is currently warming and whether the anthropocentric CO2 plays a role, however, is settled.

This is misleading. The whole world talk about both climate change and global warming, and often these are synonymous. It idea that the global warming has stopped is completely wrong, and the strongest indicator of the continuing warming is the rising global sea level. The global sea level can be thought as a global thermometer, and just like the mercury in ordinary thermometers rise, the sea level rises because the ocean water expands when it gets warmer and its volume increases when ice on land melts and pour into the seas. The temperature record also show continuous warming, as several recent scientific publications indicate.

Nobody has said that we will be dead in 10 years? Who and where?

Misleading. The December mean temperature on Svalbard was -6C in 2016. However, the temperature varies from place to place and from day to day. It is typically below 20C in somewhere in the Arctic for some days, but the general picture is that the Arctic is worming up strongly. This is documented in an upcoming report from the Artic Monitoring and Assessment Programme (AMAP.no) called Adaptive Actions for a Changing Arctic (AACA).

This statement is completely false and contradicts the observational data.

It is premature to say whether the Arctic sea-ice has a direct effect on single smog-events in Beijing. It is probably wrong. The smog tends to be caused by local pollution coupled with an atmospheric phenomenon known 'inversion' - high-pressure system sitting over the region.

This description is entirely misleading. The temperatures have come down after an El Nino event, but still follow the slow upward course.

E.g. from the thawing of permafrost.

It will reduce the critical threshold for inundation and make the margins smaller when it comes to flooding the coast line in associateion with storm surges. The question whether the storm statistics change is a different one. Both may of course happen.

Sea level rises when the mass from the land ice is displaced into the sea - it may be melt water from ice or solid ice sliding into the ocean. This is due to Archimedes principle.

The melting of the land ice and calving of glaciers reaching the fjords/sea is expected to affect the number of ice bergs drifting around. It may mean that there will be more ice bergs during the warming period. Keep in mind that sea ice (which forms when the ocean surface freezes) is very different to ice bergs (generated by the disintegration of land ice reaching the shores).

Albedo is one effect, but it is moderated by cloud cover and only is effective during summer (winter gives dark "polar nights"). Other - perhaps equally important - factors involve the effect open sea has on exchange of moisture, the way temperature varies with height, cloud cover, storm tracks, wind fetch (friction between surface and air), precipitation, waves, and ocean currents. There are also consequences for ocean CO2 uptake (acidification) and marine ecosystems.

This depends on who needs to pay for the damages. For a single site (a city), it would be correct to consider e.g. a 100-year return interval for a structure with a life time of about 100 years. But an organisation like FEMA needs to keep in mind that the number of breaching events will vary with the number of sites (cities) and need to calculate the likely number of events based on probabilities and statistics for many trials.

This provide some evidence that the rainfall levels are sensitive to various factors. We can apply a sensitivity analysis to study how sensitive the various weather statistics are to different factors, such as location, season, and time. Some parameters such as temperature autocorrelation is insensitive to different physical conditions, whereas others such as temperature, rain intensity and frequency are more sensitive (see http://goo.gl/u3IK4y). It is very likely that we will see further changes in the sensitive weather statistics in the future with a continued global warming (this is based on statistical reasoning as well as physics).

It is true that floods and storms always have occurred, but they have always ocurrred for a physical reason. This may be evidence suggesting that these phenomena are rather sensitive to a climate change, if modest natural changes in physical conditions already give rise variations in the floods and storm activity. We now know that the earth's atmosphere is changing (increased CO2 and a global warming). It would be naive to think that floods and storms do not change when importan factors change while they have always changes in the past. It is also important to think about these concept in a risk-analysis frame, and it is important to plan for various plausible scenarios.

It is expected that an increased greenhouse effect will result in wet areas becoming wetter and dry regions drier because the atmospheric overturning (convection) will respond to the atmospheric opacity [1]. Overturning means air rising in some parts and sinking in others. Rising air (convection) brings moisture aloft where it cools, condenses, forms clouds, and precipitate. The descending air is dry as it is air that previous ascended and where the moisture has precipitated out during the ascent.

[1] http://link.springer.com/article/10.1007%2Fs00704-016-1732-y

This may be true for one specific site, but when you look at many sites, you expect to see more frequent events. This is a mathematical fact and is explained by probabilities and the binomial distribution. Hence, this statement is slightly misleading, since similar events could have happened in other locations, and when applying analysis of return intervals, you need to take into consideration the number of possible multiple sites [if n=number of sites, then a binomial distribution Pr(X>4) would be more appropriate, where p=1/500, sample size=n, and X is the number of events]. However, this makes also the situation more dramatic, as a slight shift in the probability of an extreme event will pan out to cause more events somewhere in these multiple sites.

When the return-interval describes the expected recurrence frequency for a single site/region, we must expect many more occurrences over a wider area. This is explained by maths and mathematics (the Binomial distribution and probabilities). Then a small change in the probabilities (probability density function) can lead to a large increase in the number of observed events. Furthermore, the definition of climate change is indeed a changing probability density function (climate is weather statistics), which means that a past 500-year event is no longer a 500-year event, but perhaps a 100-year event. In other words, this is not surprising and is in accordance with mathematical reasoning. Actually, it is to be expected, especially since a warming leads to a higher evaporation rate and more moisture in the atmosphere. The fact that the return intervals are estimated for single sites/regions means that we can expect a dramatic increase in similar extreme weather events in the future. We can gauge this development by studying the number of record-breaking events: see http://onlinelibrary.wiley.com/doi/10.1029/2008EO410002/pdf

amplify or reduce... The fact that natural variations has such pronounced character suggests that the climate system is quite sensitive to changed conditions.

It depends on Greenland topographical features under the ice. I'm not expert on the character of the bed rock under the Greenland ice sheet, but there are accounts suggesting a depression which would take some of the melt water from the ice sheet and form a new big lake in the middle of Greenland. Hence, the number for the world ocean may be somewhat less if part of the melt water is collected by a new central lake in Greenland. https://en.wikipedia.org/wiki/Greenland%27s_Grand_Canyon#/media/File:Topographic_map_of_Greenland_bedrock.jpg

When the seasonal variation in the sea-ice cover usually is at its annual peak.

Usually the abbreviation is in capital letters: "NOAA"

Here "CO2" should be "heat". CO2-uptake in the ocean is not my field of expertise, but according to the Scripps Institute, the uptake of CO" is about 26%: https://scripps.ucsd.edu/programs/keelingcurve/2013/07/03/how-much-co2-can-the-oceans-take-up/

A side-issue: The figure also shows troposphere temperature derived from a satellite-borne instrument known as the microwave sounding unit (MSU). It shows a higher peak for the 1997-98 El Nino and not as high numbers for 2015. It's interesting looking into the question in which region of the world there is biggest difference between the upper air and surface warming, in addition to asking why.

With more cases with heat waves, the more information we have (bigger statistical sample), and the easier it gets to judge whether there is a change ongoing in their recurrence. We are usually interested in the typical pattern of heat waves, rather than "freak events".

To be picky: heat waves will always recur, but at a certain rate depending on the climate. For instance, once in every 20 years on average. They are, however, separated by more normal conditions or cold spells - just to avoid any misunderstanding.

The question of causation here really concerns the difference between weather and climate (or the difference between statistics and the individual numbers on which it is based). It is usually difficult to prove that a specific number belongs to a certain statistical character ("population"), however, it's much easier to show that the statistical properties implies certain numbers. Also it's easier to judge weather a group of numbers (a "sample") corresponds to certain statistical properties. In addition to statistical considerations ,the world also follows the laws of physics, which indeed dictate the behaviour of the greenhouse effect and its implications for the surface temperatures (http://goo.gl/Rl1aKp).

This confidence is based on both observational data, climate models, physics, and statistical thinking. Again, studies of record-breaking events provide indication that the probabilities associated with high temperatures are changing (http://goo.gl/MIb29y).

It's really mathematics, and depends on exactly how the probability density function (pdf) changes. The pdf is a result of physical processes involved, and hence can be regarded as a finger print of the climate system. There are some indication that the range of temperature variations may diminish slghtly with a future warming in the Arctic (http://goo.gl/xsbXPn), however, this may not necessarily be true for summer-time heat waves.

"Climate change" is by definition a shift in the weather statistics, such as the curve that describes the likelihood of temperatures exceeding a certain threshold. The temperature has a statistical character that is close to being bell-shaped (normal distribution), which implies that high temperatures are expected to be more frequent with a global warming - unless the typical range of temperatures (standard deviation) or shape off the curve changes. Climate is the typical character outlined by this curve (probability density function, often referred to as "pdf") describing the probabilities, whereas weather is each different data point on which this curve is based. When referring to one event - one data point - one talks about weather. Weater is not the same as climate, but they are related: climate is the expected weather. BTW, another way to keep tabs on the extremes is to count how often there are record-breaking temperatures. There is a simple mathematical law describing hoew often record-breaking events should reoccur if the climate is stable and the probabilities are not changing - more frequent records are evidence of changing conditions and more severe heat waves.

In the future, a much larger area will experience extreme hot condition than the area with reduced cold conditions. This is because if earth's geometry (a sphere); half of its surface area lies between 30S and 30N. There are critical threshold above which the temperature is getting increasingly harmful for humans (see An adaptability limit to climate change due to heat stress). We cannot assume that there will be a linear dependency. People in Texas and Florida can escape the heat in their air conditioned buildings and cars, but most people are not as lucky and have to live in hot environments. Hence, statistics based on these states are not representative for the world.

This is an absurd way to put it. There are many people who live perfectly well in cold conditions - the "cold" deaths are due to poverty and low living standards. They can be avoided through a decent welfare system and equality, as in Norway (where I live and where we hardly ever hear about cold-related deaths apart from occasional lost hiker).

This suggest that the dependency is not linear, and there is a multitude of factors involved. Hence, "cold deaths" may be a misnomer. The temperature is a moderator combined with standard of living, life-style diseases, pollution, and poverty, in addition to accidents and other weather conditions. See the above comment about slippery roads and problems related to thawing/freezing. Furthermore, the air during very cold conditions is very dry, which reduces the heat loss, whereas milder conditions are associated with more moist air that increases heat loss (even through clothing). The wind is also an important factor when it comes to the effective chill, and hence it's not the temperature alone that controls the death rate. It's a combination of many weather elements in addition to socioeconomic factors. The point is that there are many confounding effects, and we do not know how all of these play out and affect future deaths when there is a future warming.

Such numbers are very speculative in any case, as they depend on how the population is distributed and their standard of living. They ignore potential tipping points (e.g. methane in the permafrost) and other consequences (wildfires, droughts, food security). Release of methane from permafrost can boost the warming beyond that projected by the climate models.

The total number of deaths does not depend on just the percentages, but also on the population. Even a 0.5% increase in a population of a billion (say India) is much higher than 7% of 35 million (e.g Canada): 5 million > 2,5 million (this seems to be a very high number even if taken over a typical human lifetime!).

This is only one study and the conclusions should be reproduced by independent studies based on different selection of countries. It is important to assess how comparable the statistics from the different countries are (were they based on different institutions with different types of surveys and medical practices?) and how representative the statistics is. It is probable that the definition of cold death varies from country to country and is reported differently. The description "counting hypothermia, as well as increased blood pressure and risk of heart attack that results when the body restricts blood flow in response to frigid temperatures" opens up form many different interpretations, and doctors in different countries are likely to attribute causes differently. Hence, it's important with a clear definition of the term and how it and related statistics vary from country to country. Spain, South Korea and Australia have a higher standard of living than India and Africa. My concern is that there are higher proportions of in poorer countries without the means of collecting and maintaining proper statistics, or that deaths are not properly attributed since there are few doctors per inhabitant. As it stands here, there is not sufficient information to judge the veracity of these claims, which I find to be quite surprising.

This is cherry picking - even if it were true. climate change is much more than just temperature. It also affects precipitation and the lack thereof - with consequences such as floods, mud slides droughts, and wild fires. Furthermore, the cold is fairly limited to the high northern latitudes, where most people (and not so many live there, but many more in the warm tropics) are rich and have a high standard of living, which makes them able to cope. These rich countries also have the means to collect statistics. The poor developing countries often lack credible statistics, and I do not believe for a second that we have an estimate of all people who die from heat stress in Asia, Africa, and Latin America. Furthermore, climate change and increased CO2 have further impacts, such as food security and on ocean acidity. There are still knowledge gaps concerning such aspects. There are tipping points. We know for sure that the temperaure is rising and the precipitation is getting more extreme.

This account is incomplete of the whole subject, i.e. the net effect of a climate change on health. One can argue for any position by picking some data that underscores the point, ignoring other relevant aspects.

Not necessary, as deaths can be caused by avalanches, traffic accidents caused by slippery roads (under-cooled rain), slipping on ice (especially old people), being hit by falling icicles. It depends on the previous temperature. The milder winters in places like Oslo often implies more ice an/or more melting/thawing cycles.

The climate typically changes in starts and spurts. E.g. the jump in the February global mean temperature. Paeloclimatological studies suggest that the climate in the past has triggered tipping points. We know that there is a risk that some of these will be triggered.

This statement is based on a flawed paper by Douglas et al., 2007. See a paper called 'Learning from mistakes in climate research' in Theoretical and applied Climatology explaining this. Learning from mistakes in climate research

This is opposite to the findings documented in http://www.dnva.no/binfil/download.php?tid=58783

No, this is a conclusion based on serious analysis. E.g. by examining the recurrence of new record-breaking events or trends in extremes.

This is pure hand waving without any substance to support it. The comparison between climate models and measurements suggest a good agreement . The conditions in the air above the topics is complicated by the hydrological cycle, atmospheric moisture and convection.

There have been a number of reported issues with weather balloons, and they are not widely distributed around the world. They give an incomplete picture, but are not all too different to the results from climate models.

There is not a very good vcoverage of sounders around the world, and these therefore give an incomplete picture.

The use of satellite measurements to argue against an increased greenhouse effect is interesting. The satellites do not measure temperature, but electromagnetic radiation (Microwave Sounding Units), and use these measurements to estimate what the temperature must be in the air that emits this light. They use the same kind of physical laws and models to infer the temperature from the emitted light as the climate models use to infer the temperature given the change in the atmospheric transparency. It's like saying one doesn't believe in models but one believes in models. Of course, the satellites provide useful information, but they measure something different to the ground-based thermometers. Furthermore, the temperature record they provide are stitched together from many missions, and there have been many adjustments to this in the past because of drifting orbits and calibration issues.

Nevertheless, the El Nino was forecasted already in April. My judgement is that the mechanisms behind El Nino are reasonably well understood.

This is an unwarranted for accusation that is not supported by the facts.

Also the satellite-based sea surface temperatures indicate an increase.

Again, there is other independent information, such as the global mean sea level and temperature measurements from sea gliders (ARGOS floats). There are also records of glaciers and land ice.

Almost all scientific papers discuss measurement errors, but this does not mean that the conclusions are wrong. It's important to take these into account and make sure that they do not bias the results.

This "hiatus" may not be real, but an artefact caused by incomplete measurements. The thermometer readings do not cover all of the Arctic, where most of the recent warming has taken place. Other estimates, making use of additional information indicate that the gap in mearurements may be responsible an underestimate of the recent warming. This is also supported by the record of the global mean sea level, which shows an acceleration over the last years, rather than a decrease.

This fact shows that the climate is indeed sensitive to various conditions. There has always been natural climate variations, but they have always changed for a reason. They are driven by the laws of physics. now we know that one important condition is changing: CO2. It's properties as a greenhouse gas is well-established, and can be measured in a lab. It's also explained through quantum physics, and we see that Venue with a thick atmosphere with CO2 is extremely warm. It would be a paradox if the climate is sensitive to small variations in either solar activity or ocean currents, but not to this well-known factor.

No it's not business as usual. If it were, there would not be many new stories about it. One freak event is difficult to attribute to a changing climate, just as it's difficult to say whether one water drop is rain. When we see the wider context, do we see that the weather that was typical is no longer so common, and we see new weather patterns. This is the definition of climate change: the frequency of different weather types change, and we see more record-breaking events than we should expect from a climate with constant probabilities. The list of unusual events is far longer, and includes regions outside the US. December month was very unusual, and part of this may be due to the strongest El Nino ever recorded in modern history, but the global warming also plays a role in this.

Possibly the largest ever recorded with modern instruments.

Satellites measure light (microwaves) and then use a model to estimate what the temperature must be to generate this light. The equations are similar to those used in climate models to calculate the effect of increased greenhouse gases. Furthermore, the satellites measure slightly different aspects to the surface records, and the record is made of different segments from different missions stitched together. There have been a number of corrections to the satellite records in the previous years. A more reliable indicator of the global heat is the global mean sea level.

Yes, at least in parts (The Antarctic Peninsula). The ice on Antarcticta has been debated, however, and different NASA measurements indicate either a reduction in ice mass (GRACE) or that the ice surface has increased (altimetry).

The human civilization also cut down forests in Europe, which too may have had an effect, both locally (the change in surface roughness affects the wind conditions and change in vegetation affects the land-air exchange of heat and moisture) and the way the surface reflects sunlight (the 'albedo'). The deforestation also has a CO2 contribution, in addition to other human effect (agriculture and methane).

If the landforms change, that too can have an effect. E.g. opening and closing of straits, hence affecting ocean currents and circulation.

What exactly is a "left-wing idea"?

It is the weather patterns that tend to set the temperature, not so much the other way round. However, the energy balance between what is received from the sun and what the earth loses to space, too has an effect on the average temperature.

The candidate has a misguided risk perception, which is a complicated story. However, statistics offer some guidance, and there are other risks connected to health/nutrients (eg. diabetics and life style), alcohol, car accidents, guns, and pandemics, in addition to weather extremes (tornadoes, hurricanes) which are likely to take more American lives than terrorism at the moment.

Misleading. While it's true that the production of photovoltaic chips requires water, their use does not, and they need not be installed where they are produced. Solar energy can also be harvested without photovoltaic substances.

The statement about bird casualty is misleading if one does not account for birds killed in oil spill. Furthermore, far more people are killed mining for coal than setting up wind generators. Highlighting only part of the story will not promote a wiser decision.

Other countries look to California, and begin to follow its example. Innovation is an important step forward.

There is still not a well-established connection between climate change and hurricanes, although there are some indications that their intensity (not frequency, according to the IPCC) may increase in a warmer world.

There are explanations why the microwave sounding unit (MSU) data on the satellites show a slightly different picture to that of the thermometers on the ground, partly because they measure different parts of the climate system (MSU measures temperatures higher up). The most solid indication of the state of the climate is, however, the global mean seal level that responds to both warmer water and melting sea ice. The sea level does not suggest any 'hiatus'.

The statement about "a theory that is unproven" is misguided. One could use the same phrase about weather forecasting, medicine or gravity. All have in common that they involve well-known causation, but there are also some issues that cannot be entirely explained (weather forecast errors, side effects, or quantum gravity/dark matter). Is there any science that "can be proven"? The candidate should be challenged to present one. Contrary to the statement, the greenhouse effect was well understood in the first part of the 20th Century, and we have a good grasp of climate change both natural and man made.

The planet will probably be habitable, in parts. But some regions may no longer be favourable for human living, which may drive migration. It is plausible that climate change is a driver for conflicts and unrest, and there are discussions about "water wars" (which could break out between Ethiopia and Egypt or in the Middle East). However, both natural variations and man-made climate change cause natural disasters, and these are tangled together.

The knowledge about climate is quite well-established, and in fact, we know the physical principles so well that we can write computer codes that calculate both weather and climate. This is an impressive feat. Furthermore, we have also launched earth observing platforms in space and have unprecedented data, which we can use to evaluate our computations. The maturity of climatology is on par with that of medicine. It is not arrogant to say that vaccines save lives, smoking shortens life span (on average), and certain medicines will cure certain diseases. Likewise, it is not arrogant to say that we can predict the future direction of our climate, and past efforts have predicted the trend so far. We can also use our computer programs to calculate the nature of the climates on other planets and make predictions for El Nino. All scientific success stories. Then there are PR-groups which try to diminish the glory of these scientific endeavors and try to sow the misguided idea that the scientific community does not live up to its past achievements and spread misinformation about the climate science. These people do not represent the experts on this topic.

The variable climate is a proof of its sensitivity to changing conditions, and now there are undeniable evidence of a new driver: changes in the atmospheric composition due to increased concentrations of greenhouse gases. The rest of the world is moving ahead with more renewable energy sources and more modern technology. If America sticks with fossils, then that is probably going to turn into a more severe disadvantage over time. Also, a continued global warming due to increased GHG emissions is going to change the weather statistics, speeding up the hydrological cycle and cause more damage such as flooding and bush fires, depending on location. The big joker regarding the sea level is the ice cap on Greenland and Antarctica. Ice melts at high temperature, and ice sheets become unstable, disintegrate, and slide into the oceans (the sea level may increase due to Archimedes principle).

The candidate does not appreciate that the knowledge in the 1920s were not as advanced as they are today, and that since the 1970s we have launched satellites and been able to observe the earth from space and make use of computers to crack many hard scientific questions. A comparison between the 1920s weather forecasts and those of today is a good illustration. There is no hoax and no conspiracy regarding global warming.

Yes, there are natural variations, but this proves that the climate system is sensitive to perturbations, disturbances, and energy imbalances. Past variations were caused by small effects, but in comparison, the GHG forcing is both more persistent and stronger. By changing the atmospheric composition and the way the climate is affected by the energy flow, we are also changing the conditions for nature and the character of the natural phenomena.

The argument is misleading. There are studies that find that record-breaking high temperatures are more frequent that we would expect from a stable climate. When it comes to record temperatures, it's always possible to find one location where the record is not recent - that's flawed statistics ("cherry picking"). It's important to consider the pattern records for the whole planet. Heat waves are influenced by regional natural variations as well as the global state.

The statement is misleading. The rate is now 3.2 mm/year according to NASA. There has been a global warming and the sea level has increased steadily. It is hard to adapt to rising seas, as more and more land will be inundated.