2019 in Climate Science: A Continued Warming Trend and ‘Bleak’ Research

Yves here. I remember in 2007 when I was invited to an open house at the Explorers’ Club in New York City, which featured a day of presentations of scientists involved in research for that year’s Polar Year, a once-a-decade program of measurements and sightings in the Arctic. By then, it was clear to all those who’d been to the Arctic area recently, explorers as well as scientists, that warming in that polar region was already dramatic and alarming by historical standards. Yet this was still during the time when agnotologists were very successful in depicting climate findings as too speculative to take seriously.

By Dana Nuccitelli. Originally published at 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 Sciencesfound 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.

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  1. Generalfeldmarschall von Hindenburg

    The global average climate has been hotter in the distant past. In the Jurassic, it was well over 100F about everywhere. But getting used to spiders the size of dogs might take our descendants a bit of adjustment.

        1. SufferinSuccotash

          I would first check the storm drains in LA before indulging in such blanket generalizations.

    1. Ignacio

      Jurassic oil and coal is coming with a vengueance for an additional mass extintion. Well you are talking about a period of about 50 million years and surely climate wasn’t constant throughout its duration. But yet most of it was quite warm and the latitudinal temperature gradient is thougth to be much smaller in Jurassic than today. The geographic configuration of the Earth was also quite different and trying to compare today’s climate with that of Jurassic is non sensical.

  2. Susan the other

    This is good news for a worldwide consensus on the need to take action. I keep wondering what the effect was on the Pacific Ocean by Fukushima – which is still leaking into the ocean in Japan’s coastal waters. They are continuously asking the world for permission to dump all their contaminated water tanks in the ocean as well. Nobody has said, OK, sure, you just go right ahead. Kill the ocean, who needs it? Last Fall there was a mysterious blob of hot water (not attributed to the El Nino effect) cruising around the gulf of Alaska; nobody knew what it was. Strange, maybe an underwater volcano? I have a selective memory about the ocean heating up after Fukushima but I’ve never heard one word of analysis on that. Regardless of the possible heat factor for massive amounts of rad-waste, there clearly is a biological one. From seaweed to sharks. Birds and mammals. But not a word on the subject. Just wondering.

    1. Plenue

      Little to no effect. I don’t think you grasp how massive the ocean is, and how diluted everything they’re dumping into it becomes.

      1. Susan the other

        One thing we know is that the Pacific food chain is not healthy. It could be due to warming waters, but it could also be krill and tiny creatures disappearing because of Fuku. You’re right, I think the Pacific is big, but still vulnerable. The Orcas are starving. The whales are disappearing. The salmon are starving. Etc. We do know these things are happening to a wide variety of animals and if it is radwaste from Fuku it has not been diluted enough yet, and it’s gonna be there for thousands of years. Why can’t they find a better solution than just dumping it out in the ocean?

  3. Jeremy Grimm

    Climate science is complex — too complex and too frightening in some of its implications for most of the public. Many of us have little option but a degree of reliance on expert opinion, and some reliance on the opinions of those we trust or want to believe. I believe these characteristics of climate science leave it especially vulnerable to agnotology. Money fuels much agnotology, and to a lesser degree vested interest and professional bias. A great deal of money is at stake making a great deal of money available to generate agnotology and directly undermine climate research.

    I wonder if there is a public variant of the idea of a Thought Collective. The scientific community had growing evidence for climate change — declining trend of insolation, with an opposite warming due to increased CO2 concentrations known to be increasing since around the middle of the previous century. It took several decades to arrive at the present overwhelming consensus in the scientific community that the climate is warming. I believe there is a slower following process of arriving at consensus in the public sphere. Ideas in the public Thought Collective followed well behind those of the scientific Thought Collective. For a topic like climate change I believe that would be the case with or without the workings of agnotology. The public concepts of a pending crisis evolved through concerns about Nuclear War, War in Viet Nam, shifting to an “Environmental Movement”, concentrated in Silent Spring and Thinning Ozone Layer, resource depletion of Mother Earth, concentrated for a while in the Population Bomb, Global Warming, Peak Oil, and coincident [but unrelated] world-wide financial collapse, back to Global Warming and resource depletion, and overpopulation — a rough pastiche of the sequence of concerns. And all through this time other events drew attention from climate change — 9-11, the Iraq War, periodic Presidential elections, and of course a veritable flood of agnotology. I believe the public Thought Collective is finally joining the consensus of the scientific Thought Collective. But now, as the public begins to realize we are in for a ‘rough ride’, there seems to be an increasing discussion of ‘geoengineering’. The scientific community, like our public media, is well on its way to becoming a fully owned subsidiary of the Neoliberal project — and at a time when we most need the guidance of an independent scientific community. I believe the worsening prospects described by the evolving IPCC reports reflect a shift in politics made possible by the shifts in public opinions.

  4. JE

    Read an interesting sci-fi novella recently called “Permafrost” by the wonderful Alastair Reynolds. Combination of Jackpot and 12 Monkeys in that species extinction due to loss of pollinators, then plants, then small animals, etc resulted in ecosystem collapse and starvation. Solution was to travel back in time (through an interesting technological process that had just enough detail to seem plausible, shades of Primer which if you haven’t watched you should!) and ensure the “right” seeds were included in the various seed vaults. In any case, the relevance to us is that we are seeing this ecosystem collapse happening right now and we WILL NOT have a time machine to fix. How can we fix?

    We’re going to have to fix how we grow our food, meaning no or careful selection and use of pesticides.

    We’re going to have to fix what we do with our food, meaning dramatic reduction in redirection of crops to animal husbandry for meat.

    We’re going to have to fix how we manage our personal land, meaning planting “climate gardens” instead of lawns to support insects and up, reduce pesticide, herbicide and fertilizer use and increase carbon uptake.

    Obviously these are just small things nibbling at the edges of the climate emergency but we have to start somewhere and these could help the biosphere by reducing the stressors from the chemicals we use in our agriculture and lawns.

  5. Math is Your Friend

    “I keep wondering what the effect was on the Pacific Ocean by Fukushima”

    Overall? Nothing, zero, zip – way below the level that would qualify as essentially none.

    You can find sites that claim it is a huge problem, but that is about as accurate as saying vaccines are a high level pervasive and lethal risk – the province of loons and scammers. Don’t believe them.

    From a good article in deepseanews(dot)com (in 2013 – levels will be lower now):

    “Even within 300 km of Fukushima, the additional radiation that was introduced by the Cesium-137 fallout is still well below the background radiation levels from naturally occurring radioisotopes.”

    “It’s not even dangerous to swim off the coast of Fukushima. Buessler et al. figured out how much radiation damage you would get if you doggie paddled about Fukushima (Yes, science has given us radioactive models of human swimmers). It was less than 0.03% of the daily radiation an average Japanese resident receives. Tiny! Hell, the radiation was so small even immediately after the accident scientists did not wear any special equipment to handle the seawater samples”

    “To put 0.9 μSv of radiation in perspective check out this awesome graph of radiation by xkcd. You’ll get the same amount of radiation by eating 9 bananas.”

    From phys(dot)org, July 4, 2016:

    “Radiation levels across the Pacific Ocean are rapidly returning to normal five years after a meltdown at the Fukushima nuclear plant”, citing a review by the Scientific Committee on Oceanic Research.

    From oceana(dot)org, 2017/10/25:

    ” Did these leaks make Pacific seafood too dangerous eat?

    The answer, then and now, is no, scientists say. The Fukushima leaks were miniscule compared to the vast scale of the Pacific, said Nicholas S. Fisher, an expert on nuclear radiation in marine animals at Stony Brook University in New York. The disaster added just a fraction of a percent to the radiation that’s already in the ocean, 99 percent of which is naturally occurring.

    At those levels, you could eat piles of Pacific fish and have nothing to worry about from radiation, Fisher said. The dose of Fukushima-derived radiation from the average tuna fillet, he explained, “would be far less than the total radiation you’d get from eating a banana or flying in an airplane.””

    Also, consider this:

    “Super-sensitive instruments detected the cesium, but the fish weren’t unsafe to eat. “Just because you can detect it,” Fisher said, “doesn’t mean it’s dangerous.””

    Same way the cocaine on all American $20 bills won’t make you high. In both cases, it’s a comment on the insane effectiveness of current scientific instruments, not the scale of what is being measured.

    Yet you will still find junk websites with headlines like this: “28 Signs That the West Coast Is Being Absolutely Fried with Nuclear Radiation from Fukushima”.
    It’s a total lie, of course.

    From an article in sciencealert(dot)com, 2015/12/09:

    “the highest levels of radioactive contamination around 2,500 km west of San Francisco. That’s still 500 times below US government safety limits for drinking water”
    And don’t worry, the limits are very conservative and safe.

    From the wikipedia article ‘Radiation effects from the Fukushima Daiichi nuclear disaster’:

    “While there were no deaths caused by radiation exposure, approximately 18,500 people died due to the earthquake and tsunami. Very few cancers would be expected as a result of the very low radiation doses received by the public.[25] John Ten Hoeve and Stanford University professor Mark Z. Jacobson suggest that according to the linear no-threshold model (LNT) the accident is most likely to cause an eventual total of 130 (15–1100) cancer deaths, while noting that the validity of the LNT model at such low doses remains the subject of debate”

    “The LNT model did not accurately model casualties from Chernobyl, Hiroshima or Nagasaki; it greatly overestimated the casualties. Evidence that the LNT model is a gross distortion of damage from radiation has existed since 1946, and was suppressed by Nobel Prize winner Hermann Muller in favour of assertions that no amount of radiation is safe”

    That’s important, because a lot of radiation biology experts believe the LNT model is totally wrong. Unfortunately, it is invariably used when someone wants to ‘prove’ that a release of radiation has killed/will kill people.

    In a March 2019 update at ourradioactiveocean(dot)org we find:

    “the levels are still well below regulatory limits of 7,400 Bq/m3 set for drinking water (U.S. EPA). By our calculations, even if levels increase to 10 Bq/m3, swimming eight hours every day for an entire year, would only increase one’s annual dose by an amount, 1000 times less than a single dental X-ray.

    Canadian researchers measuring cesium-137 in fish, are finding similarly low levels relative to regulatory thresholds in seafood, such as salmon”

    That should be enough of sources, though you can find other scientifically accurate studies if you want. If you find a site that sounds alarmist, you’ve probably strayed into loon/scammer territory.

    I highly recommend the radiation chart at xkcd(dot)com(slash)radiation.

    It is accurate, and sometimes graphic representation helps understand the real scale of what you are considering.

    The chart provides handy reference points such as radiation from:

    – eating a banana
    – flying from NYC to LA
    – living in Denver
    – sleeping next to someone
    – living within 50 miles of a nuclear power plant for a year
    – getting a dental x-ray
    – living in a brick building
    – total dose at Fukushima Town Hall in 2 weeks following accident

    For an in depth explanation of the chart and what it means, see

    As for heating – that would be so small as to be undetectable.

  6. RubyDog

    Regarding the possible resiliency of coral reefs, could this possibly be an example of evolution in action? A small percentage of a population being resistant to heat stress, which will then repopulate in a new equilibrium? Don’t know if this is the case, but I haven’t seen much discussion of this aspect of the situation, either in this particular instance, or in a more general sense of how the stress of abrupt climate change will drive evolutionary changes.

  7. Anthony G Stegman

    It is sad to say, but there are so-called scientists who make statements of the nature that humans can survive with no other species present on the planet. That we can get by without flora and fauna because we will adapt. That pursuing profits is too important to be interfered with for any reason. Some of these so-called scientists have the ear of powerful people in business and government. And the media as well. How can we defeat these forces?

  8. chuck roast

    Here’s some climate science for you. When I was a kid in the 50’s I got off the yellow bus, grabbed my blades and stick and played hockey until it was dark. And on week ends I pushed the puck around from morning till night. From new years until late February.
    There is not even a skim of ice on the ponds and it’s going up into the 60’s next week. That’s Roast’s Science class for the day.

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