Another consequence could be to weaken storms while they move over the ocean since slower storms cause greater ocean cooling* and colder surface water decrease hurricanes strength. That would be an interesting hypothesis to test.

• Vincent et al (2012) Assessing the Oceanic Control on the Amplitude of Sea Surface Cooling induced by Tropical Cyclones. Journal of Geophysical Research

Plotting the relationship between global temperature and the logarithm of atmospheric CO2 concentration shows a strong relationship (Figure below). This is predicted by physics since CO2 is a greenhouse gas. Ian Plimer might confuse CO2 emissions and CO2 concentration in the atmopshere, which is what matters for explaining Earth’s surface temperature.

Figure - Global temperature from Berkeley Earth’s dataset versus atmospheric CO2 concentrations.

Another 'positive feedback loop' related to ocean warming and increased stratification is that this can reduce the ocean CO2 uptake, by preventing CO2 from being mixed down into the deep ocean layers.

• Matebr and Hirst (1999) Climate change feedback on the future oceanic CO2 uptake. Tellus

Enhanced stratification of the water column is indeed one mechanism that can explain the decrease in subsurface oxygen, notably in the tropics[1].

As the upper-layer of the ocean warms faster than the deeper layers, the temperature stratification increases, with the already-warm upper layer getting warmer. This enhanced thermal stratification acts as a barrier to vertical mixing, since warmer water is less dense (like when a low density fluid (eg oil) tops a high density fluid (eg water)). This stratification can prevent oxygen coming from the surface from reaching deeper layers where it gets depleted by biological activity (respiration).

As climate change proceeds, the upper-ocean layer is also expected to become fresher (less salty) in the tropics as rainfall increase, further increasing the upper-ocean stratification[2].

• [1] Behrenfeld et al (2006) Climate-driven trends in contemporary ocean productivity. Nature
• [2] Balaguru et al (2016) Global warming-induced upper-ocean freshening and the intensification of super typhoons. Nature Communications

This is an interesting rhetorical trick by Bjorn Lomborg. So far he has only supported the point that ‘as of today, the area of many Pacific islands have not decreased’. But this doesn’t mean that the islands existence is not threatened, notably in the future as sea level rise becomes more severe. So here, he is swapping a weak claim that he has supported for a much stronger one that he has not, a version of the red herring fallacy.

Scientists' comments on this article clearly show that it is also not an "entire" or "accurate" picture. So Mr Lomborg is using the very flawed reasoning he is condemning others of.

This graph of global temperature helps to put the “slowdown” of warming that occurred around the 2000-2010 period in perspective. It is misleading to put the emphasis on the slowdown without reminding that, over the long term, the temperature keeps rising. Source: NOAA

Indeed, there has been an increase in the amount of rain falling during the most extreme events across the eastern and southern US:

The bar charts show the percent changes in the annual amount of precipitation falling in very heavy events, defined as the heaviest 1% of all daily events from 1901 to 2012 for each region. Adapted from the 2014 National Climate Assessment

This chart from the National Weather Service's Storm Prediction Center shows that the amount of 'Precipitable Water' in the atmosphere over southern Louisiana (Baton Rouge) was unprecedented just before the flood.

This is indeed observed in the United States. The 2014 National Climate Assessment provides a very detailed analysis of the scientific literature on the subject of heavy downpours increase.

This is a misrepresentation of the Lords' letter. The letter builds on scientists' analyses of 2 inaccurate articles on climate change in The Times, and it asks the editor to center their coverage on the facts rather than on the viewpoints of marginal pressure group.

Misrepresenting someone's position to make it easier to attack is known as a strawman fallacy.

This statement is supported by a recent report in Nature Climate Change written by 22 scientists.

The figure below shows that global sea level rose by about 100 meters at the end of the last ice age 15 thousand years ago and that sea level had stabilized more than 5 thousand years ago. This helps clear a common misconception that current rate of sea level rise could be simply due to the end of the ice age.

The last 20,000 and the next 10,000 years of sea level. The vertical scale is measured in meters.

The trend in the number of "coastal flood days" in the US is a convincing supporting evidence of this conclusion.

Visualization created by Climate Central

The author seems to think that the 2015 heat record is no surprise since there was an El Niño event and the same happened in 1998. This is a flawed reasoning: if there were no increase in global temperature, the likelihood of breaking records after records would be very low, it is the underlying upward trend in temperature that makes breaking new records more likely everytime there is a cyclical warming event (El Niño). See this recent article for a quantification of that probability:

“In summary, our results suggest that the recent record temperature years are roughly 600 to 130,000 times more likely to have occurred under conditions of anthropogenic than in its absence.”

The graph below shows clearly that each of the 3 big El Niños on record (1982, 1997, 2015) are associated with higher global temperatures as time proceeds. Without El Niño, temperatures are higher than in 1998. source: http://www.columbia.edu/~jeh1/mailings/2016/20160120_Temperature2015.pdf

This is a rhetorical trick. Who decided that there are only two real concerns? This would assume that the other concerns about climate change are not real? For instance one of the great concern biologists express is the negative impacts on plankton and coral (hence fisheries) of warming and acidification of the ocean due to increased levels of carbon dioxide in the atmosphere see eg:

• A corrosive concoction: The combined effects of ocean warming and acidification on the early growth of a stony coral are multiplicative
• Coral Reefs Under Rapid Climate Change and Ocean Acidification
• "the imminent disappearance of modern reefs globally because of annual mass bleaching events, carbonate dissolution, and insufficient time for substantial evolutionary responses."

This is only one example that there are other concerns about global warming contrary to what the author suggest to readers here.

This is accurate. The 2014 National Climate Assessment provides a detailed analysis of the scientific literature on the subject of intense rainfall events increase in the US.

'recent' is not a precise term. On climate relevant scale, evidence shows that sea level rise has been accelerating. See for instance the figure below from Jevrejeva et al

see also:

Source: Church (2008) Understanding global sea levels: past, present and future

The candidate misunderstands how science works. Science mostly allows to gain confidence in certain statements, for instance, science allows us to say that it is beyond reasonable doubt that humans are the cause of the current warming of the planet, but it's never going to be proven in the mathematical sense of the term. Nevertheless, probabilistic knowledge is helpful to make decisions: nobody waits until it's proven that their house is going to burn to buy insurance.

That's true but, because CO2 remains in the atmosphere for centuries, the US is still the largest contributor to climate change with the largest cumulative emission between 1850 and 2011. 27% of all emissions have been made by the US. source: World Resources Institute

The best available knowledge indeed suggests that the most intense hurricanes are going to become more powerful due to global warming. See eg this synthesis by the Geophysical Fluid Dynamics Laboratory.

Sandy might not be the best example though as it was a hybrid storm (tropical/extra-tropical), for which the understanding of their response to warming is less well known.

There is no scientific study showing that natural processes could explain the continued warming we've seen over the past 40 years.

Read this article in Climate Central for more details:

nobody has come up with a natural explanation for the current warming episode that fits the observations.

To the best of my knowledge, there is no scientific evidence showing that severe storms and flood are "dramatically declining". Such a strong statement should be supported by a strong reference.

To the contrary, as the atmosphere warms, water vapor content increases, and this is allowing more extreme rainfall events, notably during hurricanes.

see eg: Trenberth (2011) Changes in precipitation with climate change

test

The figure below shows that the "explosive intensification" of the cyclone occurred right above a large anomaly of "Ocean Heat Content". This reinforces the hypothesis that subsurface temperature helped intensification of Hurricane Patricia. source: http://isotherm.rsmas.miami.edu/heat/webp/pacific.php

Indeed, intense winds associated with Hurricanes usually mix the upper-ocean vertically, bringing the cold sub-surface water to the surface, which weakens the cyclone. This mechanism is particularly effective in the East Pacific where the layer of warm water is usually shallow [1].

El Niño is associated with a deepening of the warm water layer in the East Pacific that allows to sustain much stronger cyclones.

[1] Vincent et al 2012 Assessing the oceanic control on the amplitude of sea surface cooling induced by tropical cyclones

test from working page

This is indeed supported by the scientific literature. Expected Sea level rise should significantly increase coastal 'extreme water levels'[1] and cause hundreds of billions of $ of damage in the US over the century[2].

[1] Tebaldi et al 2012 Modelling sea level rise impacts on storm surges along US coasts

[2] Neumann et al 2014 Joint effects of storm surge and sea-level rise on US Coasts

This is likely referring to the 2012 paper by Wendler. In that paper the authors conclude,

In summary, the long term observed warming of Alaska of about twice the global value, as expected by the increasing CO2 and other trace gases, is sometimes temporarily modified or even reversed by natural decadal variations.

By "temporarily" the authors were referring to only the first decade of the current century, where Alaska temperatures, like the global average, were influenced by the predominance of La Niña events. The authors clearly do not question anthropogenic global warming.

This statement is correct.

The reduction of Atlantic hurricanes due to El Niño is especially pronounced when the El Niño is associated to warming in the East Pacific[1] (as is the case of the ongoing event); the forecast for this year's hurricane activity is 'well below-average'.

[1] Kim et al 2009, Science

The Telegraph (?)

Climate Feedback has not annotated The Guardian so far. The list is here: http://climatefeedback.org/feedbacks/

Technically, the 'tool' is hypothes.is

Climate Feedback is an organized group of scientists who are using it

The Telegraph (?)

Climate Feedback has not annotated The Guardian so far.

I think there is a confusion here: it is not the oxygen or nutrients concentration in the upper-layer that affects the ocean temperature stratification but the other way around.

As climate change proceeds, the upper-layer of the ocean –that gets heated from additional infra-red radiation from above due to increased greenhouse effect– warms faster than the deeper layers. It results that the temperature stratification increases, with the already-warm upper layer getting warmer. This enhanced thermal stratification acts as a barrier to vertical mixing, since warmer water is less dense (like when a low density fluid (eg oil) tops a high density fluid (eg water)). This stratification can prevent nutrients from reaching the surface layers from the depth while they get depleted by biological activity in the upper-layer.

We currently observe an increase of the upper-ocean thermal stratification, especially in the tropics (see eg Behrenfeld et al 2006)

The original press release of the study presents "A new model of the Sun’s solar cycle". It does not mention the influence of the sun on climate nor does it predict a mini ice-age in 15 years. It appears that the Telegraph article has extrapolated the implications of the Sun's activity beyond the original report.

In the esa press release, Professor Andrew Shepherd, Director of the Centre for Polar Observation and Modelling reminds:

Although the jump in volume means that the region is unlikely to be ice free this summer, we still expect temperatures to rise in the future, and so the events of 2013 will have simply wound the clock back a few years on the long-term pattern of decline.

A simple figure here helps remind the broader context that "the volume of Arctic ice has been steadily falling since the late 1970s"

source PIOMAS

The rate of sea level rise has actually quadrupled since preindustrial times: the trend was .8 mm/yr from 1870 to 1924, 1.9 mm/yr from 1925 to 1992, and 3.2 mm/yr from 1993 to 2014. http://www.columbia.edu/~mhs119/SeaLevel/

Several studies have indeed revealed a large agreement among scientists about the existence and human origin of the Earth's surface warming.

Survey responses to "Do you think human activity is a significant contributing factor in changing mean global temperatures?", from Doran & Zimmerman (2009)

• Anderegg (2010) Expert Credibility in Climate Change. Proceedings of the National Academy of Sciences. 107(27), DOI: 10.1073/pnas.1003187107.
• Cook (2013) Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental Research Letters. 8(2), DOI: 10.1088/1748-9326/8/2/024024
• Doran & Zimmerman (2009) Examining the Scientific Consensus on Climate Change. Eos Transactions American Geophysical Union. 90(3), DOI: 10.1029/2009EO030002.
• Oreskes (2004) Beyond the Ivory Tower: The Scientific Consensus on Climate Change. Science. 306(5702), DOI: 10.1126/science.1103618.ref

For precision, the NCA report mentions a sea level rise of 1 to 4 feet with a high estimation of up to 6 feet by 2100.

more information can be found in the New York City Panel on Climate Change 2015 Report

Results by Holland and Bruyere (2013) do show an increase in the proportion of the most intense hurricanes.

It remains controversial whether these trends are due to anthropogenic climate change alone or are also influenced by data homogeneity issues (eg Landsea et al 2006)

This statement is consistent with the analysis by Grinsted et al 2012, for instance, that detects a statistically significant trend in the frequency of large surge events in the Atlantic since 1923.

This is notable since storm-surge incidence from tropical cyclones are the most damaging aspect of tropical cyclone impacts in coastal region (Knutson et al 2010)

This figure shows that sea level is indeed rising in the Vanuatu region. Part of this recent rise is attributed to anthropogenic climate change and part of it may be attributed to the natural "pacific decadal oscillation" Merrefield et al 2012

adapted from Cazeneuve and Remy 2011

That would be very useful for the Climate Feedback project. Replacing "my" by "our" commentary.

In our case, replies by others should not be visible by following the direct link (if the purpose is to discourage "trolling")

Ideally, we would need 2 "kinds of link":

• One for fellow scientists: following the link invites them to annotate and see the private + public contributions of their peers

• One for general public: following the link shows the article + public annotations of the group

This is a strong claim; a strong reference would be needed to back it up. In this article, the author provides 5 facts about the changing climate to back this assertion. This is far from sufficient to give credit to the author's claim, especially since several of these facts are only one aspect of the story, as shown by the scientists' comments below.

While the east Pacific Tropical Cyclone activity was well above average in 2014 (National Hurricane Center), this is not the case for the west Pacific, which was below average. The argument should be made clearer.

I think the figure below is instructive; It shows that 2014 is more likely than any other year to be the hottest on record. It also shows that the cone of uncertainty for 2014 temperature overlaps the ones for 2005 and 2010. 2014 cannot be said the warmest year with absolute certainty, but it is the most likely. source: Gavin Schmidt

In the Berkeley dataset too, 2014 is the warmest year on record but within uncertainty margins with 2010 and 2005.

In the Equation, MIT's Pr Emanuel and Pr Solomon comment:

"This claim amazed us, because uncertainty is a major and perhaps the major focus of scientific research on climate change and on attempts to formulate sensible policy. In the Summary for Policymakers of the latest IPCC Assessment Report, the word uncertain or uncertainty appears 36 times, and graphs pertaining to climate projections have hefty uncertainty limits and error bars. It is hard to claim that uncertainty is being hushed up."

According to MIT's Pr Emanuel and Pr Solomon, the thesis of this article "does not follow from the scientific substance of the essay". Their full argumentation is on The Equation. Here is the extract:

"Koonin notes several key scientific fundamentals. He does not deny that climate is changing, that human activities are at least partly responsible for it, or that policy formulation should take climate change into account. But the headline statement—that not enough is known about climate to warrant significant action given the risks—is a statement of values and does not follow from the scientific substance of the essay."

Overall scientific quality: 'very poor' to 'poor' (rating 0.5 / 4), according to 6 climate scientists who have evaluated this article.

Find more details in the annotations below and at https://docs.google.com/document/d/1OQSqpFUCY_cmgrANshzydOsKCx1P1VQHwbnPTjLjEsc/edit?usp=sharing

The challenges to understanding human impacts on climate are acknowledged by the scientific community. The author misrepresents the use of the term "settled" that refers to the human origin of climate change. The author here commits a straw-man fallacy as explained here: http://time.com/3445231/climate-denier-settled-science/

There are multiple lines of research showing that the warming signature of human-emitted greenhouse gas increases is much greater than the effects of natural external forcing factors over the last few decades. see for instance Wigley and Santer (2012)

This article does not acknowledge the scientific certainties in the domain of climate change science and emphasizes the uncertainties. According to the author's definition, this article would not be qualified "a serious discussion of the changing climate".

Incoherent with the main message of the article.

Misleading to focus on a 2-years recovery while sea ice extent and volume in the arctic has decreased over the past 35 years. http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/ http://www.washingtonpost.com/blogs/wonkblog/wp/2013/09/19/sorry-arctic-sea-ice-isnt-really-recovering/

CO2 does increase the acidity when dissolved in water. For reference, see for instance "Once dissolved in seawater, CO2 gas reacts with water to form carbonic acid" in Doney et al (2008) http://www.annualreviews.org/doi/full/10.1146/annurev.marine.010908.163834