We’ve Underestimated Climate Impacts

November 29, 2018

Associated Press:

WASHINGTON (AP) — Climate scientists missed a lot about a quarter century ago when they predicted how bad global warming would be.

They missed how bad wildfires, droughts, downpours and hurricanes would get. They missed how much ice sheets in West Antarctica and Greenland would melt and contribute to sea level rise. They missed much of the myriad public health problems and global security issues.

Global warming is faster, more extensive and just plain worse than they once thought it would be, scientists say now.

International negotiators meet next week in Poland to discuss how to ratchet up the fight against climate change in what’s called the Conference of Parties . The world’s understanding of global warming has changed dramatically since the first conference in March 1995. Since then the globe on average has warmed nearly three-quarters of a degree (0.41 degrees Celsius) but that’s not even half the story.

That global annual temperature increase is slightly lower than some early 1990s forecasts. Yet more than a dozen climate scientists told The Associated Press that without the data currently available and today’s improved understanding of the climate, researchers decades ago were too conservative and couldn’t come close to realizing how global warming would affect daily lives.

One scientific study this month counted up the ways — both direct and indirect — that warming has already changed Earth and society. The total was 467 .

“I don’t think any of us imagined that it would be as bad as it’s already gotten,” said University of Illinois climate scientist Donald Wuebbles, a co-author of the recent U.S. National Climate Assessment . “For example, the intensity of severe weather. We didn’t know any of that back then. And those things are pretty scary.”

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In the 1990s, when scientists talked about warming they focused on the average annual global temperature and sea level rise. The problem is that people don’t live all over the globe and they don’t feel average temperatures. They feel extremes — heat, rain and drought — that hit them at home on a given day or week, said Pennsylvania State University climate scientist Richard Alley.

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“The younger generations are growing up where there is no normal,” University of Washington public health and climate scientist Kristie Ebi said, pointing out that there have been 406 consecutive months when the world was warmer than the 20th century average.

More recently economists have joined scientists in forecasting a costly future. Yale economist William Nordhaus, who won the 2018 Nobel prize for economics for his work on climate change and other environmental issues, told the Associated Press that his calculations show climate change would cost the United States $4 trillion a year at the end of the century with a reasonable projection of warming.

The way science has looked at global warming has changed over the last quarter century because of better knowledge, better computers, better observations, more data — and in large part because researchers are looking more closely at what affects people most. Add to that what many scientists see as an acceleration of climate change and the picture is much bleaker than in the 1990s.

Back then, Michael Mann was a graduate student exploring global warming.

“I honestly didn’t think that in my mid-career we would be watching the impacts of climate change play out on my television” nor that they would be so strong, said Mann, now a prominent climate scientist at Pennsylvania State University. It is playing out with wildfires, rain-soaked hurricanes, flooding, drought, heat waves and other extreme weather, he said.

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Scientists now better understand how changes in currents in the air — such as the Jetstream — and the rain cycle can cause more extreme weather. And recent research shows how climate change is altering those natural factors.

The biggest change in the science in the last quarter century is “we can now attribute changes in global temperatures and even some extreme events to human activity,” said Sir Robert Watson, a former top NASA and British climate scientist who chaired the United Nations’ Intergovernmental Panel on Climate Change from 1997 to 2002.

With improved knowledge and tools, scientists can better understand extreme weather such as hurricanes and droughts, and they can run complex computer simulations that attribute extremes to human-caused warming from the burning of coal, oil and natural gas, Watson said.

Scientists attribute extreme events to human-caused warming by comparing what happened in real life to simulations without heat-trapping gases from fossil fuels. They’ve concluded climate change has caused more rain in hurricanes Harvey , Maria , Katrina and others .

Studies have shown climate change has worsened droughts, downpours and heat waves, such as the Russian one in 2010, that have killed thousands of people. And they have linked climate change to the growing amount of land in the western United States burned by wildfire, which wasn’t considered a big climate issue a couple decades ago, said University of Utah fire scientist Phil Dennison.

From air pollution triggered by wildfires that caused people in Northern California to don breathing masks to increased asthma attacks that send children to the hospital, medical experts said climate change is hurting people’s bodies.

“We’re seeing surprises,” public health professor Ebi said. “We’re projecting changes and we’re seeing them sooner than we expected.”

That includes once-tropical disease carrying mosquitoes in Canada and warm water shellfish bacteria showing up in Alaska , she said.

Massachusetts General Hospital emergency room physician Dr. Renee Salas, who wrote a chapter in the medical journal Lancet’s annual climate health effects reports, said these aren’t abstract statistics, but real patients.

“When I had to tell a tearful mother that I needed to admit her 4-year-old daughter for an asthma attack, her fourth visit in a week, climate change was truly top of my mind because I knew her disease was due to rising pollen levels,” Salas said.

Massive ice sheets in western Antarctica and Greenland are melting much faster than scientists figured a quarter century ago.

Antarctica has lost nearly 3 trillion tons of ice since 1992, enough to cover Texas nearly 13 feet (4 meters) deep, scientists reported in June. Greenland has lost more than 5 trillion tons in the same period.

Melting in Antarctica and Greenland in the last few years “literally doubled our projections of the sea level rise at the end of this century,” said Mann of Penn State.

Non-experts who reject mainstream science often call scientists “alarmists,” yet most researchers said they tend to shy away from worst case scenarios. By nature, scientists said they are overly conservative.

In nearly every case, when scientists were off the mark on something, it was by underestimating a problem not overestimating, said Watson, the British climate scientist.

But there are ultimate worst cases. These are called tipping points, after which change accelerates and you can’t go back. Ice sheet collapses. Massive changes in ocean circulation. Extinctions around the world.

“In the early 1990s we only had hints that we could drive the climate system over tipping points,” said Jonathan Overpeck, environment dean at University of Michigan. “We now know we might actually be witnessing the start of a mass extinction that could lead to our wiping out as much as half the species on Earth.”

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19 Responses to “We’ve Underestimated Climate Impacts”


  1. Richard Alley recently said that sea level rise could be as much as 15 to 20 feet by the end of the century. You can see this in a video at: https://www.rollingstone.com/politics/politics-news/climate-change-sea-level-rise-737012/

  2. Ron Benenati Says:

    well, if the world had backed up climate scientist, followed through with the Kyoto Protocol, funded science rather than threatening their lives, spent less or nothing on the contrived climate-denial propoganda that turned public support into cold molasses…perhaps they could have zeroed in a bit more…
    none-the-less, who would have listened?

  3. Sir Charles Says:

    Updates from
    Today’s Climate
    11/29/2018

    World Health Leaders: Climate Change Is Putting Lives, Health Systems at Risk

    International health experts says climate change has ushered in a global health crisis that will worsen as temperatures rise and stress health care systems. Of all the climate-related health impacts, heat waves and infectious diseases currently pose the greatest immediate risks to public health.

    (InsideClimate News)

    Climate Change Could Crash These Important Fisheries, Study Warns

    Worsening greenhouse gas emissions are creating a double whammy for Atlantic and polar cod populations, with global warming and more acidic water projected to undercut their reproduction by nearly two-thirds in some areas and alter their habitats dramatically, new research shows.

    (InsideClimate News)

    World Faces Difficult Task at Poland Climate Talks

    Three years after the global climate deal in Paris, world leaders are gathering to agree on the fine print. Top of the agenda will be finalizing the so-called Paris rulebook, which determines how countries have to count their greenhouse gas emissions, transparently report them to the rest of the world and reveal what they are doing to reduce them.

    (Associated Press)

    EPA Chief: Trump Administration May Intervene in Next Climate Study

    President Trump didn’t like the results of the most recent National Climate Assessment, saying that he didn’t believe the dire warnings. His EPA chief, Andrew Wheeler, says Trump might seek greater influence in future climate reports.

    (Politico)

    Past Four Years Were the Hottest on Record, Data Shows

    This year is expected to be the fourth warmest year on record, with average temperatures around the world about 1°C above pre-industrial levels. The past four years have been the hottest on record, and the 20 warmest have occurred in the past 22 years.

    (The Guardian)

    EU Aims to Be ‘Climate Neutral’ by 2050

    European Union leadership says its members could reduce emissions to net zero by 2050, but it would take significant commitment from member states. Germany is worried that further cuts would threaten its industries, and others such as Poland are still reliant on coal and would object to more stringent fossil fuel restrictions.

    (BBC)

  4. Sir Charles Says:

    Beware the rise of the radical right
    Academic freedom is on the hit list when radical politicians gain office — as they have done in Europe.

  5. ecoquant Says:

    It’s not scientists’ fault they missed these. For many, being conservative and not being alarmist or extreme is/was the definition of scientific practice. So projections were linear, and based primarily upon elaborate projections of a historical record.

    The climate system is not linear, not if forced strongly as we are, and not over a long enough period of time.

    Moreover the constant need to be able to debate climate denialists, and shills of opposed interests means that only the most defensible projections are put out there, irrespective of what personal experience and scientific history and tradition say.

    Note the FEMA flood maps are no better, and often worse: These have no capability of using new insights into future climate, insisting that projections be based upon actual records of flooding in order to estimate what future waters might be.

    One of the several things we are giving up is the linear world of climate. Akin to “global weirding” this might be called “global blinding”: Records and traditions and patterns don’t matter as much anymore as they once did because Things Have Changed.

    • Roger Walker Says:

      “…not being alarmist or extreme is/was the definition of scientific practice”

      Sure – up to a certain point. But I think they ought to have challenged the “alarmist” label much sooner. I’m no scientist – I’m probably a good example of the “informed layman”. But I don’t need to understand the science as such. I only need to take the time and the trouble to find and read the scientists’ conclusions.

      I’ve given talks for local associations (here in the west of France) and one of the points I hammer home is the difference between “alarmist” and “alarming”. The former is the boy who cries wolf for the pleasure of seeing everyone scurry around; the latter says, “Look, the wolf is there! FFS open your eyes!”

      • Sir Charles Says:

        Good point. I think there is a similarity. Many people in the US don’t understand the difference between ‘social’ and ‘socialist’. Denmark is surely not a ‘socialist’ country, but Oprah Winfrey calls it just that.

  6. redskylite Says:

    Agree the underestimation is not the Scientists nor the IPCC’s fault, for all the power of today’s supercomputers and knowledge gained through paleontology, more and more evidence points that this industrial period is completely unique in Earth’s history. The magnitude of changes that the industrial revolution has wrought is yet to fully sink in. Mankind has made profound changes in around a century that in the past has taken up to millions of years. How can any human or supercomputer confidently predict the result of this ? Scientists are not oracles. Humans seem to expect immediate reaction to their activities and are completely out of tune with the time-spans nature works at.

    • grindupbaker Says:

      In terms of climate models it requires N**4 speed increase to reduce the distance grid scale by N and run at the same fraction of real time as before. So reducing from the present 90 km horizontal to 9 km horizontal and also reducing the vertical slice size by factor 10 would require 10,000x the prior computing speed. I don’t know how much parameterization (averaging in a box) can be replaced with simulated reality with each reduction factor of grid size but as you see the computing power increases required are huge.

  7. Roger Walker Says:

    I’ve read NCA4 overview and for me it replaces the IPCC’s AR5 as ‘the reference’ in matters of climate change.

    This is hardly surprising because the IPCC works to a very limited remit defined by its political masters:

    • it only reports every seven years – an eternity in terms of scientific research;

    • it has been widely criticized for being too conservative, and rightly so. AR4, for example, made virtually no mention of the impact of ice melt because “there wasn’t enough data.” AR5 was hardly better, despite the availability of more than 20 years of hard data which, if they’d analysed it differently, would have revealed the beginnings of an exponential curve;

    • the graphics in the IPCC’s 2018 interim report are remarkably similar to those I calculated in 2013 – using their own data;

    • and of course the structure and the wording of IPCC reports are ‘negotiated’ with the politicians.

    NCA reports, on the other hand, are published every four years and therefore based on more up-to-date research. The politicians don’t get to interfere. And in NCA4 particularly, the scientists say clearly what they’ve been thinking for years – if not decades.

    In addition to presenting new and wider reaching information, NCA4 uses entirely different language. Look at the tenses of the verbs. Where the IPCC says, “such and such an impact could occur,” NCA4 says, “… these phenomena will impact.”
    I find it significant too that NCA4 devotes considerable space to the social impact of climate change, especially on those populations who are the most vulnerable and, almost by definition, the least well-resourced in terms of ‘mitigation’ and ‘adaptation’. The word ‘equity’ figures prominently.

  8. ecoquant Says:

    David Suzuki has a recent post where he quite aptly calls all this the “climate crunch”.


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