Arguments
2019 in climate science: A continued warming trend and 'bleak' research
Posted on 7 January 2020 by dana1981
This is a re-post from Yale Climate Connections
The last six years have been the six hottest globally ever recorded by humans.
2014 had been the hottest year up to that point, until the record was shattered in 2015, and again in 2016 thanks to a monster El Niño event. El Niños bring hot water up to the ocean surface where it warms the temperature of the surface air that most directly influences and interests humanity. Next came 2017, the second-hottest year recorded by humans, but far and away the hottest that wasn’t influenced by an El Niño event. And then 2018, the fourth-hottest overall, but by far the hottest year on record that was cooled by a La Niña event.
And now 2019, warmed by a moderate El Niño event and as such not as hot as 2016 with its monster El Niño; but it was nevertheless the second-hottest year on record, and quite possibly the second-hottest in the history of human civilization.
As global warming has continued, so too has the volume of peer-reviewed reports and studies published by climate scientists documenting its accelerating impacts. Here are some of the most influential climate change research papers published in calendar 2019.
United Nations IPCC reports
The U.N. Intergovernmental Panel on Climate Change published two special reports in 2019, one documenting climate change impacts on land and food security, the other on the oceans and ice. Both reports warned that the risks of severe climate change impacts will grow as global temperatures warm beyond the 1.5 and 2 degrees Celsius (2.7 and 3.6 degrees Fahrenheit) targets set in the 2015 Paris climate agreement. Food security will become increasingly threatened, as will important marine species and ecosystems like coral reefs. Melting ice sheets will continue to accelerate sea-level rise, and permafrost, once-but-no-longer-permanently frozen, will release increasing amounts of previously trapped carbon into the atmosphere as it thaws. Those are but a few of the growing climate change threats documented in the IPCC special reports, which were widely characterized as being “bleak.”
A report produced by the United Nations Environment Programme (UNEP) in November 2019 also documented that countries’ planned fossil fuel extraction efforts will far overshoot the Paris climate targets. While global fossil fuel production and associated carbon emissions must peak and begin to fall within a few years to meet those goals, countries instead plan to continue increasing fossil fuel extraction through the year 2040, which would be consistent with a pathway of more than 3 degrees C (5.4 degrees F) hotter than pre-industrial temperatures by the end of the century. This report highlighted an important disconnect between countries’ goals to curb global warming and their plans to continue extracting ever-more fossil fuels.
Scientists are becoming increasingly concerned and outspoken about this disconnect. In November, more than 11,000 scientists signed a letter published in the journal BioScience declaring “clearly and unequivocally that planet Earth is facing a climate emergency.”
According to Altmetric, which tracks which scientific research most captures the public’s interest each year, the UNEP report was the fourth-most influential scientific paper published in 2019, with coverage in 527 news outlets and 8,290 tweets.
Studies on the climate of the ‘Common Era’
Climate scientists’ best global temperature reconstructions cover the past 2,000 years, a period also known as the “Common Era.” Several studies investigating the details of temperature changes over the Common Era were published in 2019.
In July, the journal Nature published a study that looked for significant natural climate change events during that period, such as the Medieval Warm Period (approximately the years 950 to 1250) and the Little Ice Age (approximately 1300 to 1850). The authors reported that they “find no evidence for preindustrial globally coherent cold and warm epochs … the warmest period of the past two millennia occurred during the twentieth century for more than 98% of the globe. This provides strong evidence that anthropogenic global warming is not only unparalleled in terms of absolute temperatures, but also unprecedented in spatial consistency within the context of the past 2,000 years.”
According to Altmetric, that Nature report was the 28th-most influential scientific paper of 2019, with coverage in 264 news outlets and 1,930 tweets.
The Past Global Changes consortium of more than 5,000 scientists from some 125 countries published its newest reconstruction of global temperatures over the Common Era in Nature Geoscience in July. That group similarly concluded, “The largest warming trends at timescales of 20 years and longer occur during the second half of the twentieth century, highlighting the unusual character of the warming in recent decades.”
A study published in Quaternary Science Reviews in March 2019 sought to determine whether the arrival of Europeans in the Americas in 1492 and the subsequent large-scale massacres of native populations (an estimated 56 million deaths by 1600, shrinking the indigenous population 90%) had a detectable influence on the global climate. Forests re-grew on land previously altered by humans, which the authors estimated led to “5?ppm CO2 additional uptake into the land surface in the 1500s compared to the 1400s … The Great Dying of the Indigenous Peoples of the Americas resulted in a human-driven global impact on the Earth System in the two centuries prior to the Industrial Revolution.”
According to Altmetric, the Quaternary Science Reviews study was the 46th-most influential scientific paper of 2019, with coverage in 101 news outlets and 4,141 tweets.
Research in 2019 on coral reefs
Coral reefs are among the most diverse ecosystems in the world and a critical source of food and habitat for about 25% of the ocean’s fish. They’re also among the species and ecosystems most vulnerable to the changing climate, and thus are the subject of much scientific research.
Researchers published a study in Nature Climate Change exploring the resilience of Great Barrier Reef corals that had survived an extreme hot year in 2016 only to be hard-hit again by extreme heat the following year. The results offered a rare source of encouragement, finding that corals that survived 2016 without bleaching were also more resistant to bleaching in 2017.
According to Altmetric, that study was the 14th-most influential scientific paper of 2019, with coverage in 47 news outlets and 6,228 tweets celebrating the good news.
The 22nd-most influential paper, with coverage in 98 news outlets with 4,812 tweets, however, painted a bleaker picture for the Great Barrier Reef. Published in Nature in April, authors of the study found that larval recruitment (the settlement of fish and coral larvae necessary for a healthy ecosystem) declined 89% in 2018 after those two extreme hot years. This study received a boost of media attention in November, when in a Nature Communications study, scientists used underwater speakers to replicate the sounds of healthy coral reefs. They found that twice as many fish arrived and stayed as in areas where no sound was played. This finding provides some hope that coral reef ecosystem recovery could be accelerated – if the reefs aren’t continually battered year after year by extreme heat.
The year’s major findings on flora and fauna
Land species also were the subject of several influential papers published in 2019. One published in Science in July estimated the number of trees that could be planted and the amount of carbon they could pull out of the atmosphere. “Ecosystems could support an additional 0.9 billion hectares of continuous forest. This would represent a greater than 25% increase in forested area, including more than 200 gigatonnes of additional carbon at maturity.” Those numbers would represent a removal of about one-third of cumulative human carbon emissions through current times, and 20 years’ worth at the current rate of about 10 billion tons of carbon per year. However, some scientific groups disputed the accuracy of these estimates, which also rely on foresting every available hectare of land. Nevertheless, the study was Altmetric’s 9th-most influential of 2019, with coverage in 330 news outlets and 6,518 tweets.
Two 2019 studies finding alarming rates of species extinctions were also high on Altmetric’s list. One published in Biological Conservation in April found “dramatic rates of decline that may lead to the extinction of 40% of the world’s insect species over the next few decades” as a result of various human factors including climate change, which “is particularly important in tropical regions.” This study was Altmetric’s 13th-most influential of the year, with coverage in 251 news outlets and 4,679 tweets.
In the second study, published in Science in October, researchers surveyed bird species and found “a net loss approaching three billion birds, or 29% of 1970 abundance” as a result of “habitat loss, agricultural intensification, coastal disturbance, and direct anthropogenic mortality, all exacerbated by climate change.” That study was Altmetric’s 34th-most influential paper, with coverage in 259 news outlets and 1,465 tweets.
These studies are consistent with the “bleak” notion that Earth is currently on a path to its sixth mass extinction event. (An upcoming post at this site will look in depth at major 2019 research reports addressing wildlife and climate change.)
The past year’s major findings on melting ice
Several high-profile papers in 2019 also addressed the accelerating melting of ice and its implications. One, published in Science Advances in June, found that since 2001, Himalayan glaciers have been losing ice at a rate twice as fast as they had in the prior 25 years. Those glaciers provide an important source of water for billions of people in China, India, Pakistan, and several other countries in the region. The paper was Altmetric’s 65th-most influential, with coverage in 294 news outlets and 414 tweets.
A January study published in the Proceedings of the National Academy of Sciences found that over the past decade, Antarctica has been losing ice at a rate six times faster than during the 1980s. And another paper published in PNAS in June asking experts about future sea-level rise projections found that because of accelerating ice sheet declines, a rise of more than two meters (about six feet) by the year 2100 remains within the realm of possibility. Those were the 86th- and 70th-most influential papers of 2019, respectively.
Overall, the second-hottest year was, sadly but perhaps unsurprisingly, full of bleak news in climate science research. Climate scientists’ findings and reports increasingly raise the alarm of a “climate emergency” or “climate crisis” – terms that many in the mainstream media began to use regularly in 2019 without feeling the need to qualify or use quotes. Because of climate scientists’ increasingly concerning research findings and language, climate crisis is becoming more widely accepted and used as the norm.
I sent this comment to the SS inbox, but seems relevant here as well.
I really wish the scientific community in the US and those communicating the +1°C change (and +1.5°C target limit) would convey what this really means to land-dwellers in the US and around the world.
It is well established from observations, and from projections/models, that land temperatures (where most of us live, and where we grow our crops and livestock) increase at roughly 2x the rate that global temperatures rise.
Thus, discussing a "+1.5° target limit" is very misleading to most Americans (and becomes a talking point for deniers that it's too small to worry about).
EVERY time the +1.5°C target limit is mentioned, it should be pointed out that this implies a +3°C increase over land, where you live. And for those in the US who are much more familiar with the Farenheit scale, that becomes nearly +5.5°F.
EVERY time we talk about a +1.5° target - explain that this equates to +5.5°F over land.
The +1°C we are already experiencing means +2°C over land, and that is already over +3.5°F; people are lulled to sleep with the +1.0 and +1.5°C global increases and are completely unaware that we're talking much larger (2x larger) amplification over land.
I strongly suspect that if you start explaining to staple crop farmers and livestock farmers they will see +5.5°F with the current target (which we may not even meet), they will raise their eyebrows at that.
In a nutshell:
+1.5C global = +3C land = +5.4F land
+2C global = +4C land = +7.2F land
+2.5C global = +5C land = +9F land
+3C global = +6C land = +10.8F land
Make a simple graphic; educate people, so they understand when someone dismisses a +1.5C global rise, it's actually MUCH more pronounced than that for where they live and play!!!
Tree planting is obviously useful for soaking up some emissions, but these tree planting schemes do still need a dose of cold, hard realism, because there's a serious risk people will assume they can solve a huge part of the climate problem thus obviating us from the urgent requirement to reduce emissions.
For example the article usefully says "Luedeling also takes issue with the map that Crowther’s team ultimately produced that shows where additional trees could grow globally. Many of those areas aren’t available for tree regrowth because they’re already in use.” Those regions include land used for livestock grazing, as well as populated areas such as Kinshasa, the capital of Democratic Republic of Congo... etcetera.
Nobody seems to mention that there will also be competing uses for waste lands and cattle grazed lands, from both biofuels production and for food production for a population heading towards 11 billion people by the end of the century. Obviously the food supply will take precedence over trees, because it simply has to.
And obviously there will be huge demands for timber for construction although the bright spot is there are alternatives like steel framing.
In addition there is Red Barons suggestion that properly rotationally grazed land can also sequester carbon, which has at least some evidential backing ( a bit more research would be helpful).
Planting forests looks like a useful wedge measure to soak up some carbon, but relying on it as a major player capable of soaking up a third of emissions to date doesn't stand up to scrutiny.
Cooper13 seems to have made an extremely good point.
I think the paper referenced above in the article is of enormous use to those who come up against the 'Mediaeval Warm Period was global' argument.
"No evidence for globally coherent warm and cold periods over the preindustrial Common Era
Raphael Neukom, Nathan Steiger, Juan José Gómez-Navarro, Jianghao Wang & Johannes P. Werner"
Agriculture, the 'bad boy' of many ecologists, could be a major part of the solution of putting carbon back into the soil which bad agricultural practices stetching back a few millenia has vented into the atmosphere. Read the three books by David R Montgomery, Dirt, Growing a Revolution and The Hidden Half of Nature for chapter and verse. What is great about the approach he reports on is that it improves the bottom line of farmers from the small-holding life-style-blocks right up to giant agri-businesses.
@Cooper13 Where is the evidence that land warms twice as much as the global average? And why would land temperatures increase twice as fast as ocean temperatures?
I've heard that the Arctic is warming unusually fast, but not all land.
@anticorncob6:
Also, WoodForTrees has a site you can plot data from GISTEMP and CRUTEM yourself (GIS is global temps, CRUTEM is land-only). Plotting those from 1880 on, you can see the land temperature increase is larger (not exactly 2x, but perhaps 1.7x, as overal rise is 1 to 1.1C, land only is closer to 1.7-1.8C). So, 2x may exaggerate the issue somewhat, but the effect is larger than 1.5x.
Mods - can you eliminate that oversized graph, or shrink it in my post above?
Also, @anticorncob6: here is a link to the NASA climate data, and you can look at trends for global land+ocean vs. just global over land.
Add in the trendline function, and the trend per decade for global is +0.7C/decade; for global land only it is 0.11C/decade, or a factor of 1.6
That is close to my guesses in the above post; yes, it isn't exactly 2. So if that's too much of an exaggeration, then use 'greater than 1.5x', which are still concerning numbers.
Forgot that link:
https://www.ncdc.noaa.gov/cag/global/time-series/globe/land/ann/7/1880-2019?trend=true&trend_base=10&begtrendyear=1880&endtrendyear=2019
Coopee13 @6,
You say 2x may be an exaggeration, but NOAA data for Global Land 1975-2018 yields a linear trend of +0.30ºC/decade while Global Ocean yields +0.13ºC/decade.
anticorncob6 @5,
You ask why the differential between land & ocean. This is because the ocean depths are still warming up and so cooling the ocean surface temperatures.
@MA Rodger and @anticorncob6:
Rodger- you are correct; looking at 1975 to 2018, where the increases have become fairly linear (likely because of the continually increasing forcing with higher GhG concentrations), the trend is absolutely 2x.
We do need to be careful with cherry-picking a particular starting point, as that does alter the slopes somewhat. Choosing more like 50 years, 1968-2018 we get slopes of:
+0.17°C/decade (+0.31°F/decade) for Land AND Ocean (global)
+0.29°C/decade (+0.52°F/decade) for Land ONLY
So, 2x isn't all that bad a guess, really. Certainly the land-amplification (which is just an average - it's not the same everywhere) is somewhere between 1.5x and 2x of the global number. If you're a conservative farmer, concerned about your livelihood, I'd be going with the 2x assumption and acting accordingly (e.g. making your legislative representatives aware that you CARE about this and want action taken to minimize it)
Here are direct links to the page with those calculations, 1968-2019, as the pages will load with those selections saved:
Land & Ocean
Land ONLY
So, my 'back of the napkin' guess in the first post may not be all that 'alarmist', the numbers indeed support it. Pass that along to people you encounter on this topic - perhaps SS will run a short post on this, as it's more about communicating the understanding than some magical revelation here. They will likely be able to cite sources which better clarify the background science, as well.
-Cheers
@anticorncob6
Here's the whole article, with sourcing and a snippet:
In the past six decades, land temperatures have risen about 2.3°F, a warming rate of nearly 0.4°F a decade, as the top chart shows. That’s nearly double the temperature rise of the ocean, which is 1.25°F per decade. Moreover, in the past 30 years, the rate of warming appears to have sped up even more, with land temperatures rising more than 0.6°F a decade. That’s now a bit more than double the ocean warming.
thinkprogress.org/global-warming-now-twice-as-fast-over-land-than-the-ocean-nasa-chart-shows-52b4afe01345/
Cooper13
You said at the start @ 6 that "It is well established from observations, and from projections/models, that land temperatures (where most of us live, and where we grow our crops and livestock) increase at roughly 2x the rate that global temperatures rise."
I think this is wrong but it is maybe a sort of "typo" on your part. Global temperatures are the average of the land and ocean temperatures arent they? The data suggests land temperatures are increasing maybe 1.5% faster than the average global temperatures (eyeballing your graphs)
Dont get me wrong. Your basic point is really important namely that land temperatures are increasing significantly faster than both ocean temperatures as you mention elsewhere, and the "average temperatures" we typically use in discussion that combine land and ocean. By using this average of land and oceans we miss the fact that land is heating significantly faster.
@nigelj
Subsequent posts linked to data for the past 5-6 decades indicate the Land:Global ratio for warming is indeed approximately 2.
1.6 is the lower end of the estimate - if you look at longer time-scales back to the beginning of the 20th century. But where most of the warming has occurred (past 5+ decades), it is a ~2x ratio; that is based upon the linear trendlines, not 'ballparking' off graphs.
Cooper @13, yes I see it now at comment 10, and your 2x looks feasible. Its just you jumped around a bit comparing different things.
This looks like something that should be in the general media. Most people would assume that statements of warming made in the media apply to land. Its a seriously misleading thing. Must mention it to our local science writer in our main newspaper.
As a relative newcomer to the climate change issue, I find it surprising that our preferred figure of merit is global mean surface temperature (GMST). Is it advisable for the IPCC to state their goals in terms of limiting global warming to a GMST rise of 1.5 degree C, or even a 2.0 degrees? People I talk to are not alarmed by those figures. They see that much change every day of their lives.
Climate deniers find it very easy to raise doubt about whether the temperature measurements are accurate; whether calculating a global aveage is meaningful; whether that small a temperature difference is dangerous; and whether "that small an effect" is just due to natural fluctuations. We end up debating whether models are validated and how much committed heating there is. [Have we already passed 1.5 degrees?]. It sometimes seems like a losing battle.
Moreover, none of the consequences of global warming arise from GMST. They arise from the addition of heat to the oceans, the ice sheets, the soil and the atmosphere.
Wouldn't Earth's Energy Imbalance (EEI) or ocean heat content (OHC) be more compelling figures of merit? These numbers are enormous; the equivalent of detonating a nuclear weapon every few seconds. They are more easily attibutable to fossil fuel. They have direct impact on consequences such as sea rise, ice melting and drought. And future projections are less dependent on models.
I would be vey interested in hearing other opinions on this question.
Very Respectfully, --Richieb1234
Ritchieb,
I understand your frustration. Imagine how Michael Mann and James Hansen feel after trying to deal with this issue for 30 years.
The Earths energy imbalance and ocean heat content have only been accurately measured for a few years, less than 2 decades. There are no proxies to extrapolate the data into the far past. There are still large error bars for these measurements. The deep ocean (over 2,000 meters) is poorly measured.
By contrast, there are accurate thermometer temperature measurements going back to 1880. Proxies have been found that accurately go back over 800,000 years and much further with poorer resolution. There is a reason deniers deny the Hockey Stick graph so much. Current estimates of the world temperature anomaly have error bars of hundredths of a degree. People do not understand what 2E18 joules means. I have a very strong scientific background and 2E18 joules does not have much meaning to me except it is a lot of energy.
As you point out, many people do not recognize that 2C will have big effects. I remember 10 years ago I wondered if I would live to see obvious sea level rise, more fires, increased storms, Antarctica melting and other effects (I expect to live to 2045). Here in just 2020 we see all of those effects already. Scientists seriously underestimated what effects 1C would have. Remember that only a 5C decrease in temperature means a mile of ice over New York! The last time carbon dioxide was over 400 ppm sea level was 20 meters higher!! (that will not happen overnight, do you care about your decendants in 300 years?).
It was recently pointed out here that 2C world average means 4C over land which is 7.2F over the entire USA!! I knew all the math but had not connected all the dots to see how much change F 2C really was. We are heading for most likely 3C by 2100 (more after that!) which is 11F every day all summer! Are your audiences really prepared for 11F? How could you visit Los Vegas half the year?
The deniers will deny whatever measurement scientists make. EEI and OHC would make no difference. I try to focus on the effects we all currently see. Point out that they will get worse over time. Here in Florida people moan about 10 inches of sea level rise. Can Miami Beach continue to exist when they already have 8 inches of water in the streets? Fires worldwide are obvious and people know about them. Storms like Harvey, Florence and Sandy are unprecedented and people worry. They have had three 500 year storms in the last 3 years in Houston.
If you are speaking to the public use the numbers you are most comfortable with. One talk I heard used pictures of people and had no data. The speaker found people did not relate to data no matter what it described but related to stories of people whose homes were flooded or Koalas killed in the thousands. One moving picture showed the speakers' friend who lost their home in the Paradise fire and is now a climate refugee in the USA. This October I went diving in North Cuba and Cozumel, both world class coral reefs. Over 90% of the coral was dead in both areas.
Use what you find relates best to people. If you find you are successful in reaching people come back here and tell us what works best for you.
richieb1234 @15, if we used ocean heat content the denialists would probably say "and look that leads to just 1 degree, of warming" (or some other small number) and all the usual related blather. So we end up back where we started.
It might also create the impression we are trying to scare people by cherrypicking the most scary looking data, and if people start to think we are selectively doing this, scientists credibility gets shot to pieces.
The best thing is just to stick to the obvious thing people relate to which is temperatures like MS points out. Clearly 1.5 or 2 degrees doesn't sound very scary until you look into the consequences and how serious they are. I also like to point out that if we don't stop temperatures getting to 1.5 degrees, it could lock in tipping points that might take us over 5 degrees c eventually and 5 degrees should get peoples attention.
I totally understand your frustrations and I have experienced all the same things, but I think we just have to stick to the conventional approach and hope it convinces enough people. Once we try to be too clever in our approach to the thing it could backfire.
Denialists are frustrating. Even if we only convince a few of the hard core denialists its something, and it will probably only be a few.
Also people won't tell you if you are being persuasive, because people are too proud to publicly admit they have changed their mind. This doesn't meant they haven't changed their mind.
nigelj & michael sweet:
Thanks for the feedback and helpful suggestions. My comment was not meant to express frustration. I really do think that energy/heat is a better measure of the warming than temperature. I will have to give iit more thought. meanwhile, I will use more pictures and fewer numbers.
In Canada, there is a media campaign declaring that Canada is warming twice as fast as the rest of the world.
CANADA WARMING TWICE AS FAST AS THE REST OF THE WORLD
Sorry, I meant for this to be one post...
I am uncertain about this claim "twice as fast", shortly after this declaration, the Liberals announced a climate emergency. I am not sure what this amounts to but the rhetoric has certainly notched up recently.
When I visit Www.yourenvironment.ca I can look at the recorded temperature of any city in Canada dating back upto 150 years and I was expecting the hockey stick graph I see so regularity here, there and everywhere. But the graph is completely flat. No discernable rise in temperature in any city in any province.
What am I to believe? Who am I to believe?
[DB] The accuracy of the climate temperature station record in Canada is verified and affirmed, here:
"One last point from this CCC analysis of temperatures: it's also worth noting the magnitude of recent Arctic warming. The slope of the 30-year trend in this region is 5 to 6 C/century — a rate of warming that's much higher than the rest of the world."
Blueball. A number of things. Firstly, Canada gets that headline because it has significant area in the arctic and that is the portion of earth that is warming the fastest. (eg see the video graphic at https://climate.nasa.gov/). Not a lot of cities up there.
Secondly there a couple of issues with the graphs at your link. They show monthly average daytime highs not average temperature. The mechanism of AGW warms night faster than day (eg see this paper of observations). They also present the temperatures with a range that covers all of Canada. This is good for looking at temperatures between places but given large year to year variation, it makes trends difficult to spot. You can make any trend disappear if you make the y axis big enough.
I dont know of any website that will give you quick graph of any weather station, but this website shows how to download and graph any station you like.
"El Niños bring hot water up to the ocean surface where it warms the temperature of the surface air that most directly influences and interests humanity."
Wouldn't it be more accurate to say "El Niños slow down the rise of cold water to the ocean's surface?"
Why would that be case? I dont follow your argument, why would cold water be rising?
scaddenp,
because of the Walker circulation and the thermocline angle between the 2 sides of the Pacific. See here and the Wiki.
Ah ok. Thanks for that. Understand the suggestion which makes sense.