Global Warming: Getting worse

I recently noted that there are reasons to think that the effects of human caused climate change are coming on faster than previously expected. Since I wrote that (in late January) even more evidence has come along, so I thought it was time for an update.

First a bit of perspective. Scientists have known for a very long time that the proportion of greenhouse gasses in the Earth’s atmosphere controls (along with other factors) overall surface and upper ocean heat balance. In particular, is has been understood that the release of fossil Carbon (in coal and petroleum) as CO2 would likely warm the Earth and change climate. The basic physics to understand and predict this have been in place for much longer than the vast majority of global warming that has actually happened. Unfortunately, a number of factors have slowed down the policy response, and the acceptance of this basic science by non scientists.

A very small factor, often cited by climate contrarians, is the consideration mainly during the 1960s and 1970s, that the Earth goes through major climate swings including the onset of ice ages, so we have to worry about both cooling and warming. This possibility was obviated around the time it was being discussed, though people then may not have fully realized it at the time, because as atmospheric CO2 concentrations increased beyond about 300ppm, from the pre-industrial average of around 250–280ppm (it is now at 400ppm), the possibility of a new Ice Age diminished to about zero. Another factor mitigating against urgency is the fact that the Earth’s surface temperatures have undergone a handful of “pauses” as the surface temperature has marched generally upwards. I’m not talking about the “Faux Pause” said to have happened during the last two decades, but earlier pauses, including one around the 1940s that was probably just a natural down swing that happened when there was not enough warming to swamp it. A second pause, shorter, happened after the eruption of Mount Pinatubo, in 1991.

Prior to recent anthropogenic global warming, the Earth’s surface temperature has squiggled up and down do to natural variability. Some of these squiggles were, at least reionally large enough to get names, such as the “Medieval Warm Period” (properly called the “Medieval Climate Anomaly”) and the “Little Ice Age.” When the planet’s temperature started going distinctly up at the beginning of the 20th century, these natural ups and downs, some larger and some smaller, caused by a number of different factors, eventually became imposed on a stronger upward signal. So, when we have a “downward” swing caused by natural variation, it is manifest not so much as a true downturn in surface temperatures, but rather, less of an upward swing. Since about a year and a half ago, we have seen very steady warming suggesting that a recent attenuation in how much temperatures go up is reversing. Most informed climate scientists expect 2015 and even 2016 to be years with many very warm months globally. So, the second factor (the first being the concern over the ice age as possibly) is natural variation in the Earth’s surface temperature. To reiterate, early natural swings in the surface temperature may have legitimately caused some scientists to wonder about how much greenhouse gas pollution changes things, but later natural variations have not; Scientists know that this natural variation is superimposed on an impressive long term upward increase in temperature of the Earth’s surface and the upper ocean. Which brings us to the third major factor delaying both non-scientists’ acceptance of the realities of global warming, and dangerous policy inaction: Denialism.

The recent relative attenuation of increase in surface temperatures, likely soon to be over, was not thought of by scientists as disproving climate models or suggesting a stoppage of warming. But it was claimed by those denying the science as evidence that global warming is not real and that the climate scientists have it all wrong. That is only one form of denialism, which also includes the idea that yes, warming is happening, but does not matter, or yes, it matters, but we can’t do anything about it, or yes, we could do something about it, but the Chinese will not act (there is little evidence of that by the way, they are acting) so we’re screwed anyway. Etc.

The slowdown in global warming is not real, but a decades-long slowdown in addressing global warming at the individual, corporate or business, and governmental levels is very real, and very meaningful. There is no doubt that had we started to act aggressively, say, back in the 1980s when any major hurdles for overall understanding of the reality of global warming were overcome, that we would be way ahead of where we are now in the effort to keep the Carbon in the ground by using clean energy. The precipitous drop we’ve seen in photovoltaic costs, increases in battery efficiency and drop in cost, the deployment of wind turbines, and so on, would have had a different history than they have in fact had, and almost certainly all of this would have occurred faster. Over the last 30 or 40 years we have spent considerable effort building new sources of energy, most of which have used fossil Carbon. If even half of that effort was spent on increasing efficiency and developing non fossil Carbon sources, we would not have reached an atmospheric concentration of CO2 of 400ppm in 2015. The effects of greenhouse gas pollution would be less today and we would not be heading so quickly towards certain disaster. Shame on the denialists for causing this to happen.

I should mention a fourth cause of inappropriate rejection of the science of climate change. This is actually an indirect effect of climate change itself. You all know about the Inhofe Snowball. A US Senator actually carried a snowball into the senate chamber, a snowball he said he made outside where there has been an atypical snowfall in Washington DC, and held it aloft as evidence that the scientists had it all wrong, and that global warming is a hoax. Over the last few years, we have seen a climatological pattern in the US which has kept winter snows away from the mountains of California, contributing significantly to a major drought there. The same climatological phenomenon has brought unusual winter storms to states along the Eastern Seaboard that usually get less snow (such as major snow storms in Atlanta two winters ago) and persistent unseasonal cold to the northeastern part of the US. This change in pattern is due to a shift in the behavior of the Polar jet stream, which in turn is almost certainly caused by anomalous very warm water in parts of the Pacific and the extreme amplification of anomalous warm conditions in the Arctic, relative to the rest of the planet. (The jury is still out as to the exact process, but no serious climate scientists working on this scientific problem, as far as I know, doubts it is an effect of greenhouse gas pollution). This blob of cold air resting over the seat of power of one of the more influential governments in the world fuels the absurd but apparently effective anti-science pro-fossil fuel activism among so many of our current elected officials.

Climate Sensitivity Is Not Low

The concept of “Climate Sensitivity” is embodied in two formulations that each address the same basic question: given an increase in CO2 in the atmosphere, how much will the Earth’s surface and upper ocean temperatures increase? The issue is more complex than I’ll address here, but here is the simple version. Often, “Climate sensitivity” is the amount of warming that will result from a doubling of atmospheric CO2 from pre-industrial levels. That increase in temperature would take a while to happen because of the way climate works. On a different planet, equilibrium would be reached faster or slower. Historically, the range of climate sensitivity values has run from as low as about 1.5 degrees C up to 6 degrees C.

The difficulty in estimating climate sensitivity is in the feedbacks, such as ice melt, changes in water vapor, etc. For the most part, feedbacks will increase temperature. Without feedbacks, climate sensitivity would be about 1.2 degrees C, but the feedbacks are strong, the climate system is complex, and the math is a bit higher level.

As time goes by, our understanding of climate sensitivity has become more refined, and it is probably true that most climate scientists who study this would settle on 3 degrees C as the best estimate, but with wide range around that. The lower end of the range, however, is not as great as the larger end of the range, and the upper end of the range probably has what is called a “fat tail.” This would mean that while 3 degrees C is the best guess, the probability of it being way higher, like 4 or 5, is perhaps one in ten. (This all depends on which model or scientist you query.) The point here is that while it might be 3, there is a non-trivial chance (one in ten is not small for an extreme event) that it would be a value that would be really bad for us.

Anyway, Dana Nuccitelli has a recent post in The Guardian that looks at climate sensitivity in relation to “The Single Study Syndrome.”

There have been a few recent studies using what’s called an “energy balance model” approach, combining simple climate models with recent observational data, concluding that climate sensitivity is on the low end of IPCC estimates. However, subsequent research has identified some potentially serious flaws in this approach.

These types of studies have nevertheless been the focus of disproportionate attention. For example, in recent testimony before the US House of Representatives Committee on Science, Space and Technology, contrarian climate scientist Judith Curry said,

Recent data and research supports the importance of natural climate variability and calls into question the conclusion that humans are the dominant cause of recent climate change: … Reduced estimates of the sensitivity of climate to carbon dioxide

Curry referenced just one paper (using the energy balance model approach) to support that argument – the very definition of single study syndrome …

…As Andrew Dessler told me,

There certainly is some evidence that climate sensitivity may be below 2°C. But if you look at all of the evidence, it’s hard to reconcile with such a low climate sensitivity. I think our best estimate is still around 3°C for doubled CO2.

So there is not new information suggesting a higher climate sensitivity, or a quicker realization of it, but there is a continuation of the consensus that the value is not low, despite efforts by so called luke-warmists or denialists to throw cold water on this hot topic.

Important Carbon Sink May Be Limited.

A study just out in Nature Geoscience suggests that one of the possible factors that may mitigate against global warming, the terrestrial sink, is limited in its ability to do so. The idea here is that as CO2 increases some biological activities at the Earth’s Surface increase and store some of the carbon in solid form as biomass. Essentially, the CO2 acts as plant fertilizer, and some of that Carbon is trapped in the detritus of that system, or in living tissue. This recent study suggests that this sink is smaller than previously suspected.

Terrestrial carbon storage is dependent on the availability of nitrogen for plant growth… Widespread phosphorus limitation in terrestrial ecosystems may also strongly regulate the global carbon cycle… Here we use global state-of-the-art coupled carbon–climate model projections of terrestrial net primary productivity and carbon storage from 1860–2100; estimates of annual new nutrient inputs from deposition, nitrogen fixation, and weathering; and estimates of carbon allocation and stoichiometry to evaluate how simulated CO2 fertilization effects could be constrained by nutrient availability. We find that the nutrients required for the projected increases in net primary productivity greatly exceed estimated nutrient supply rates, suggesting that projected productivity increases may be unrealistically high. … We conclude that potential effects of nutrient limitation must be considered in estimates of the terrestrial carbon sink strength through the twenty-first century.

Related, the Amazon carbon sink is also showing long term decline in its effectiveness.

Permafrost Feedback

From Andy Skuce writing at Skeptical Science:

We have good reason to be concerned about the potential for nasty climate feedbacks from thawing permafrost in the Arctic….research bring good news or bad? [From recent work on this topic we may conclude that] although the permafrost feedback is unlikely to cause abrupt climate change in the near future, the feedback is going to make climate change worse over the second half of this century and beyond. The emissions quantities are still uncertain, but the central estimate would be like adding an additional country with the unmitigated emissions the current size of the United States’ for at least the rest of the century. This will not cause a climate catastrophe by itself, but it will make preventing dangerous climate change that much more difficult. As if it wasn’t hard enough already.

Expect More Extreme Weather

Michael D. Lemonick at Climate Central writes:

disasters were happening long before humans started pumping heat-trapping greenhouse gases into the atmosphere, but global warming has tipped the odds in their favor. A devastating heat wave like the one that killed 35,000 people in Europe in 2003, for example, is now more than 10 times more likely than it used to be…. But that’s just a single event in a single place, which doesn’t say much about the world as a whole. A new analysis in Nature Climate Change, however, takes a much broader view. About 18 percent of heavy precipitation events worldwide and 75 percent of hot temperature extremes — defined as events that come only once in every thousand days, on average — can already be attributed to human activity, says the study. And as the world continues to warm, the frequency of those events is expected to double by 2100.

Melting Glaciers Are Melting

This topic would require an entire blog post in itself. I’ll give just an overview here. Over the last year or so, scientists have realized that more of the Antarctic glaciers are melting more than previously thought, and a few big chunks of ice have actually floated away or become less stable. There is more fresh water flowing from glacial melt into the Gulf of Alaska than previously thought. Related to this, as well as changes in currents and increasing sea temperatures, sea level rise is sparking sharply.

The Shifting Climate

I mentioned earlier that the general upward trend of surface temperature has a certain amount of natural variation superimposed over it. Recent work strongly suggests that a multi-decade long variation, an up and down squiggle, which has been mostly in the down phase over recent years, is about to turn into an upward squiggle. This is a pretty convincing study that underscored the currently observed month by month warming, which has been going on for over a year now. It is not clear that the current acceleration in warming is the beginning of this long term change … that will be known only after a few years has gone by. But it is important to remember that nothing new has to happen, no new scientific finding has to occur, for us to understand right now that the upward march of global surface temperatures is going to be greater on average than the last decade or so has suggested. We have been warming all along, but lately much of that warming has been in the oceans. Expect surface temperatures to catch up soon.


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Thanks for this informative and well presented if worrying update on Global Overheating*, Greg Laden. Shared.

* "Warming" is in my view to a misleadingly mild way of describing it. Were not getting nice and warm - our planetary biomes are overheating dangerously and rapidly.

By Astrostevo (not verified) on 04 May 2015 #permalink

Quote: "This blob of cold air resting over the seat of power of one of the more influential governments in the world fuels the absurd but apparently effective anti-science pro-fossil fuel activism among so many of our current elected officials."

It's almost as if Nature had a ironic sense of humor.

This issue really does horrify me. It is the most significant important issue of all our lives and yet so few seem to notice it and it has just become a background reality getting far less attention than it needs.

People seem to forget how much damage is already in the pipeline, how much heating and drastic negative change is already inevitable and happening. It's like we are all in a slow motion car crash affecting the whole globe and everyone and every thing on it - but there are still idiots at the wheel who don't accept that its even happening at all even when we can see it now and even now insist on not putting their feet on the brakes that will at least mean a (global!) car crash at fifty kmph instead of a hundred and fifty.

If the "conservatives" and uber-capitalists are worried by steps we could take now to mitigate the severity of what's coming, how are they going to react in a few decades or who knows, much less time, when truly drastic measures will almost certainly be needed - but which we could've avoided by making milder changes sooner.

(Say, metaphorically speaking, braking at 200 kph with milli-seconds to spare and still slamming into the wall at 180 km ph or choosing whether to hit a brick wall or a crowd of innocent people and then a brick wall instead of easing off the throttle and spinning the car into a run off area as we could've done back in the 1980's..)

By Astrostevo (not verified) on 05 May 2015 #permalink

I'm with you aStevo! But, I'm equally worried by ecosystem/habitat damage and biodiversity loss. This study on the prospects for survival of many large herbivores (>100kg!) is pretty depressing.

My hope today is that maybe having the discussion about human-caused extinctions and biodiversity loss might sensitize people to climate as something we need to address as a global problem. (Yes, there's always the chance they'll just run away from more terrible news.)

In some ways those issues are easier to relate to at a human or landscape scale, so maybe people will perceive them as too valuable to ignore, or will learn that with some effort we could actually address them. I think part of the problem with climate as an issue is that it's too vast and abstract for many people to get their heads around. The creativity of climate and environmental deniers never fails to amaze me though.

I think that the emphasis of denialist arguments is moving away from the “pause” and focusing more on energy poverty and temperature adjustments. To me this change is not an indication of success, but of increasing desperation. The denialists are losing the war, but they and the fossil fuel interests they serve have already done incalculable damage.

How bad this damage is becomes even more clear when we consider that surface warming thus far has amounted to 0.85°C, and that there's an additional 0.6°C of inevitable warming in the pipeline. A heroic effort might keep us under 2°C, but recent research seems to show that dangerous effects, especially at the local level, begin at around 1.5°C. In his description of the Nature Climate Change paper on extreme weather, Chris Mooney wrote:

“Future warming will shift the odds even further, the new study finds. 'The probability of a hot extreme at 2C warming is almost double that at 1.5C and more than five times higher than for present-day,' the authors write. This statistic, they add, illuminates a sharp difference between trying to hold global warming to 1.5 degrees C — as many African nations, small island states, and other countries seek — and 2 degrees C, a target generally more supported by large industrialized countries, such as the U.S. and European nations.

'This result has strong implications for the discussion of different mitigation targets in climate negotiations, where differences between targets are small in terms of global temperatures but large in terms of the probability of extremes,' note Fischer and Knutti.”…- global-warming-has-already-dramatically-upped-the-odds-of-extreme-heat-events/

Another paper

focuses specifically on the social injustice inherent in the higher target. The author's remarks to Science Daily are even more trenchant:

“The official global target of a 2°C temperature rise is 'utterly inadequate' for protecting those at most risk from climate change, says a lead author on the Intergovernmental Panel on Climate Change (IPCC), writing a commentary in the open access journal Climate Change Responses...

Tschakert says: 'Using a figure for average global warming may indeed be the most convenient and compelling means to discuss the severity of climate change impacts, but not only does it inadequately capture the complexity of the climate system, it poorly reflects locally experienced temperature increases and the extreme and large variation across regions -- no single person or any species
faces a global average.' ”

By cosmicomics (not verified) on 05 May 2015 #permalink

À propos my comment above, in a radio interview yesterday James E. Hansen called the 2°C target “a prescription for disaster, and he described how the current trend in sea level rise would affect coastal cities:

A partial transcript is available here:…

Hansen has already argued that a 1°C increase above current levels would be dangerous:

“These conclusions, together with the discussion above about time constants, imply that global warming of more than 1◦C above today’s global temperature would likely constitute “dangerous anthropogenic interference [DAI]” with climate.”

Referring to the Reasons for Concern/burning embers diagram, Michael Mann expressed a similar point of view:

“Given that risks to threatened systems, and risks associated with extreme weather enter into the “red zone,” and the distribution of impacts begins to weigh heavily toward being adverse across diverse regions at ≈1 °C additional global mean warming (defined relative to a 1990 baseline), it would seem difficult for the risk averse among us to accept anything much above that as the standard for DAI. At 2 °C warming, we find that aggregate impacts begin to weigh toward the negative in most metrics, and the risk of large-scale discontinuities becomes nontrivial.”

By cosmicomics (not verified) on 05 May 2015 #permalink

I have always been a strong believer in the fact that our climate i changing at an alarming rate. We as humans are ruining the only planet we have to live on. This post is very thorough and informative. How do you feel we should go about spreading the word to the rest of the population to be more Earth conscience?

I find it amusing that you blame "denialists" for the fact that we did not see an investment in clean energy in the 1980's. As someone who lived through that era I can say that denialists were a non-issue in that era. The reason the investment was not made was that the worlds was undergoing a global recession, it was considered expensive and there lacked a political will to do anything that would slow down the economy and hurt the economy’s chances of recovery. To claim “denialists” had anything more than a marginal or ancillary effect is simply a creative rewriting of history that can be called nothing less than a form of fan fiction. The reality is that in the developed world environmental issues have always taken a backseat to economic ones. Every major environmental advance has taken place during years of prosperity and years of economic downturn are always related to downturns in environmental and ecological awareness. It is fine to bemoan the errors of the past, it is not fine to re-write history ignoring the fact that many of your readers were alive and active when that history took place.

please provide references to this sentence, if you are willing to stand by it "Scientists have known for a very long time that the proportion of greenhouse gasses in the Earth’s atmosphere controls (along with other factors) overall surface and upper ocean heat balance"

By stephan weaver (not verified) on 12 Jun 2015 #permalink

We've been hearing these dire warnings for 30 years and people are still buying this garbage? When are you people going to pull your heads out of your asses and realize you are being manipulated?

By Ricardo Montelban (not verified) on 11 Nov 2015 #permalink

We’ve been hearing these deniers discount warnings for 30 years and people are still buying their garbage? When are you anti-science people going to pull your heads out of your asses and realize you are being manipulated?

By Brainstorms (not verified) on 11 Nov 2015 #permalink

The real reason Conservatives don't *get it* and I know from first hand experience is that they don't go to college and for a very good reason because college is now a debt trap for more then 50 percent of Americans rich or poor. Free or bond.

So as a result they don't know how to read a graph and can't get higher end tech jobs.

I was taught to read graphs so I can figure out the gist of it pretty fast and did well in school when it comes to charts and graphs where a lot of my peers just struggled and struggled and I'm autistic too which should've screwed me.

That is the main answer to why people don't believe in GW because they can't and won't understand charts and graphs so it looks like gobbly gok to them.

It has nothing to do with *religion* which is political scapegoating by the media to avoid the issue. It has nothing to do with *traditionalism* which doesn't even mean anything and can mean everything.

When you put too many cultures into one pot without any organization you get a rat race and then there winds up being NO culture that has any identify left.

Scientific evidence shows putting too many rats in a cage disease becomes rampant and they all wind up fighting each other which is what we are being subject to.

In many modern cities when natural disasters strike in other nations that has also proven the case but most people only pay attention to sensational headlines instead of seeing the forest for it's trees.

By SortingHat (not verified) on 07 May 2016 #permalink

To Blair. Couldn't put it better myself. Too many other issues were far more important and now we have a down economy so people and big business will become stingy as they are afraid of losing their 4 big mansions.

They will have to tell their peers they lost 1 mansion and a power boat.

By SortingHat (not verified) on 07 May 2016 #permalink