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“Climate Change is Now More Certain Than Ever,” New Report Says

Image Credit: NASA

Melting sea ice is an iconic example of climate change. Image Credit: NASA

Climate change is one of the defining issues of our time. So begins the latest report by the U.S. National Academy of Sciences and the United Kingdom’s Royal Society. The two institutions agree: climate change is not only indisputable, it’s largely the result of human activities.

The bulk of the 36-page report is presented in a question-and-answer format, making it a good bed-side read. But in case you don’t want to have nightmares about surging temperatures or polar bears alone on breaking ice caps, we’ll leaf through the intriguing points here.

In a forward to the report, Dr. Ralph J. Cicerone, president of the National Academy of Sciences, and Sir Paul Nurse, president of the Royal Society argue that multiple lines of evidence show that humans are changing Earth’s climate. This is now more certain than ever.

They are careful to include a caveat: “The evidence is clear. However, due to the nature of science, not every single detail is ever totally settled or completely certain. Nor has every pertinent question yet been answered.” Areas of active debate include how much warming to expect in the future and the connections between climate change and extreme weather events such as the frequency and intensity of hurricanes, droughts and floods.

Earth’s global average surface temperature has risen as shown in this plot of combined land and ocean measurements from 1850 to 2012, derived from three independent analyses of the available data sets. The temperature changes are relative to the global average surface temperature of 1961?1990. Source: IPCC AR5, data from the HadCRUT4 dataset (black), UK Met Office Hadley Centre, the NCDC MLOST dataset (orange), US National Oceanic and Atmospheric Administration, and the NASA GISS dataset (blue), US National Aeronautics and Space Administration.

Earth’s global average surface temperature has risen as shown in this plot of combined land and ocean measurements from 1850 to 2012, derived from three independent analyses of the available data sets. Image Credit: National Academy of Sciences / The Royal Society

But the first question: is the climate warming? goes without debate. Yes. Earth’s average surface air temperature has increased by about 0.8 degrees Celsius since 1900, and the last 30 years have been the warmest in 800 years. It’s the most rapid period of sustained temperature change in the scale of global history, trumping every ice age cycle.

Recent estimates of the increase in global temperature since the end of the last ice age are four to five degrees Celsius. While this is much greater than the 0.8 degree Celsius change recorded over the last 100+ years, this change occurred over a period of about 7,000 years. So the change in rate is now 10 times faster.

Of course an increase in temperature goes hand in hand with an increase in carbon emissions. Greenhouse gases such as carbon dioxide absorb heat (infrared radiation) emitted from the Earth’s surface. Increases in the atmospheric concentrations of these gases trap most of the outgoing heat, causing the Earth to warm. Human activities, especially the burning of fossil fuels have increased carbon dioxide concentrations by 40 percent between 1880 and 2012. It is now higher than at any time in at least 800,000 years.

And if the rise in carbon emissions continues unchecked, warming of the same magnitude as the increase out of the last ice age can be expected by the end of this century.

The report continues to ask more controversial questions. Take as an example the question: Does the recent slowdown of warming mean that climate change is no longer happening? The short answer is no. Decades of slow warming and accelerated warming occur naturally in the climate system. Despite the slower rate of warming the 2000’s were still warmer than the 1990’s

The new report builds upon the long history of climate-related work from the United Nations’ Intergovernmental Panel on Climate Change. So while some have argued it doesn’t add anything new to the wealth of climate science data available, it does help make that data more succinct and available to the public. Its goal is to help inform decision makers, policy makers, educators and all other individuals.

The report concludes by noting available options to citizens and governments. They can simply wait and accept the losses, they can change their pattern of energy production, they can attempt to adapt to environmental changes as much as possible, or they can seek as yet unproven geoengineering solutions.

No matter which option we choose, one thing remains certain: the Earth is warming at a tremendous rate and we are the cause.

The paper is available for download here.

About 

Shannon Hall is a freelance science journalist. She holds two B.A.'s from Whitman College in physics-astronomy and philosophy, and an M.S. in astronomy from the University of Wyoming. Currently, she is working toward a second M.S. from NYU's Science, Health and Environmental Reporting program. You can follow her on Twitter @ShannonWHall.

Comments on this entry are closed.

  • sed1701 February 28, 2014, 10:14 AM

    I think that Universe Today should also look at the works of Dane Wigington with regards to climate change due to climate engineering.

  • joseluis February 28, 2014, 11:23 AM

    The conspiratorial theory of the supposedly ongoing geoenginnering conspiracy or “climate engineering” seems to me to be deeply paranoid, very confusing and most probably is completely unfounded. I checked it here: http://www.geoengineeringwatch.org/
    I do not agree that such controversial theories should be covered by Universe Today. There are more than enough other web pages covering all those theories in all their possible -and limited- depths

  • Steven February 28, 2014, 2:41 PM

    I certainly agree that CLIMATE CHANGE is a matter of FACT. In fact, throughout the history of the planet, CLIMATE CHANGE has been the normal situation.

    The part that I am uncertain of is how much of the current period of Global Warming is due to our exit from a recent glacial period and how much is anthropogenic. I don’t think we have enough information to say that it is ALL anthropogenic and I don’t think we can possibly say that there is no anthropogenic component.

    It is fairly obvious that major climate changes (both warming and cooling) have occured suddenly (on the order of a hundred years or so) in the Quaternary and Holocene Periods of the current geologic era (Cenozoic) along with long term trends in between glacial periods.

    The Milankovich cycle theory predicts that this particular interglacial may last another 50,000-100,000 years and MORE WARMING is COMING. Milankovich cycle theory does NOT include and of the the possible effects of anthropogenic warming or cooling.

    “What does The Milankovitch Theory say about future climate change?
    Orbital changes occur over thousands of years, and the climate system may also take thousands of years to respond to orbital forcing. Theory suggests that the primary driver of ice ages is the total summer radiation received in northern latitude zones where major ice sheets have formed in the past, near 65 degrees north. Past ice ages correlate well to 65N summer insolation (Imbrie 1982). Astronomical calculations show that 65N summer insolation should increase gradually over the next 25,000 years, and that no 65N summer insolation declines sufficient to cause an ice age are expected in the next 50,000 – 100,000 years ( Hollan 2000, Berger 2002). and we may expect continued warming through the next major part of that period.”

    So, the question is not whether there is anthropogenic warming but to what extent is man influencing the current cycle of warming that is occuring. Perhaps we are contributing far less than we think. We do not know with any certainty that the warming that occurs during an interglacial is steady over long periods or if it accelerates as the Earth warms and glaciers disappear or if it comes in spits and spurts, perhaps, dependent on other factors such as volcanism, meteor impacts, small (or maybe large) changes in the solar output or other external factors (for instance, if the sun were to pass through a locally dusty or gassy patch in the sun’s orbit around the Milkyway galaxy that could alter the amount of solar radiation that the Earth receives.).

    Since do not have a complete history of how an interglacial “works”, I am not willing to say with any certainty that all (or even most) of the global warming in recent time (since 1850) is due to the activities of man.

    Now, I would also say with certaintly that adding significant amounts of Carbon Dioxide, Methane and other gases more or less indescriminately to the atmosphere was NOT and is NOT a good idea but a greater question is whether the bulk of greenhouse gasses come from Fossil Fuels (Coal, Oil, Natural Gas) or whether the bulk comes from other sources such as ruminant animals (Us, Cows, etc), insects (termites, ants, etc.) and burning of wood/plant material/dung which may contribute far more to net greenhouse gas growth than fossil fuels.

    Instead of concentrating all of our efforts to control greenhouse gas emissions to Fossil Fuel sources (which leaves the bulk of greenhouse gas emissions untouched), I would think we should be looking at other sources just as much — along the lines of POPULATION CONTROL (if there are far fewer of us we will generate less emissions), finding an alternative to the raising of livestock on massive scales and burning wood/plant material/dung for cooking and or heat.

    We can all pretend that this planet can support a continuously expanding population but anthropogenic global warming is just a small part of the many symptoms of a vastly overpopulated planet.

    Unless/until we address the overpopulation issue, our planet is ultimately doomed – whether it be anthropogenic global warming or anthropogenic destruction of the entire planetary ecosystem which, unfortunately, is well on its way. One only needs to look at the collapse of global fisheries and the loss of forests to see that current population levels are unsustainable let alone future increases. If we control anthropogenic sources of greenhouse gases and do nothing about overpopulation then what happens when we remove the last of the wild fish, crustaceans, mammals, etc. from the sea? Can anyone say SOYLENT GREEN? Anthropogenic global warming will be the least of our concerns if we don’t address OVERPOPULATION just as urgently.

    • Ron February 28, 2014, 8:35 PM

      Steven, You present some grate facts and I 100% agree with your overpopulation warnings. However, you weaken your argument with some questionable conclusions based on a lack of specific facts concerning why human intervention is so conclusive. First of all, read “The Two-Mile Time Machine”. That will put a solid framework around your statements concerning orbital drivers. Secondly, the last 50 or so years have strongly deviated from those orbital drivers. And, finally, this article clearly states that the rate of warming we are currently experiencing is much greater than any rate spanning glaciacian periods over the last 800,000 years. These facts make it a strong conclusion that humans are primarily responsible not just for warming, but for the RATE of warming we are experiencing.

    • Olaf February 28, 2014, 8:51 PM

      Ok lets assume that some part of the global warming is a natural cycle.
      Then what? Just sit here and do nothing because it is not our fault?
      Lest get cooked because it is a natural way. It is probably Gods plan to cook us anyway.

      If you want POPULATION CONTROL then you should join the Illuminanti.
      Population control is the same excuse as just sit there and do nothing and blame it on all the other people except of taking responsibility.

      The fight against global warming also reduces air pollution.
      The fight against global warming also forces us to search for new ways and new technologies.
      The fight against global warming forces us to think about our planet and stop deforestation.

  • Aqua4U February 28, 2014, 4:27 PM

    With reportedly peta tons of methane being released from below once frozen permafrost in the arctic and subarctic, the ‘trigger’ has been pulled. We can debate all you want about whether or not man played a role (OF course he did!), but you might eventually agree when the forthcoming climatic upheaval becomes deadly for millions….

  • Jason Blankenship February 28, 2014, 4:44 PM

    I keep coming back to all the weather reports, the past couple of years, that show record cold, record sea ice, record lake ice, and record levels of snowfall and cold temperatures. Granted, there are heat records also, but look at the current winter in the northern hemisphere, it has been one for the record books, literally, as far as cold goes. If there truly is warming occurring, it sure isn’t consistent, because the US and northern Europe has seen some extremely cold winters, and last year, where I live, it was the 4th coldest summer on record. I’m not convinced (yet) that we’re warming, let alone that it is humanity causing it.

    • Ron February 28, 2014, 8:29 PM

      Jason, You are confusing weather with climate. Any given year has a lot of random variability. But, average the trends over 10, 20, or more years and you start to see climate changes. Even so, 2013 comes in as the forth hottest year in recorded history.

      • jjasensio March 1, 2014, 8:58 AM

        Hello Jason, this winter has been very cold in parts of North America and Europe. But do not think that the world ends there. I am living in Germany. This winter has been up to now more than 3 degrees warmer than the average. In fact, except 1 or 2 weeks, thare has been really no winter up to now. Do we have to conclude from this data from Germany (and many other places in EU) that the temperature of the Earth has increased more than 3 degrees? I do not think so.
        Look at the global figures, not at local figures. And just think logically: we started from the end of the 19th century to throw to the atmosphere big ammounts of CO2 that was locked up to then under the earth (along with many other gases). The increase of 40 % of the concentration of CO2 has for sure something to do with that, And there is no discussion about the greenhouse effect of the CO2, I think. Usually 1+1 ist 2 or near 2. Logicallz speaking, we are part of the problem, most probably a big part.
        This is not ideology, this is just logic.

  • fritzilla February 28, 2014, 11:32 PM

    Oh, now I am glad we have settled this science. Now we can all stop debating it…

    Seriously folks, can we keep the politics off of one of the nicer science sites? I get enough political agendas and pseudo climate change science all day. It’s nice to have a site not get so consumed in a controversial subject like global warming.

  • FarAwayLongAgo March 1, 2014, 5:28 AM

    This is a blog about space exploration and controversial climate politics. Why not add a third totally unrelated topic? Something about religion and wars in Asia would fit in nicely in the mix. Those who are interested in astronomy and space flight can find other sites.

    • jjasensio March 1, 2014, 9:04 AM

      Well, I suppose that an entry about the greenhouse effects in the climate of Venus or Mars is considered planetology. But speaking about that in the Earth is not planetology?
      If the blog starts to speak about what the goverments should do, I can agree with you that this is perhaps not the place. But speaking about concentration of gases, temperature trends, where these gases come from, etc, is something that we are reading so often here, related to Mars, for example. Why not about Earth? Politics comes afterwards, when we have to decide to do or not to do something

      • FarAwayLongAgo March 1, 2014, 9:38 AM

        The blog never ever speaks out against the fanatic political extremists who suggest to by political force abolish most agticulture, most energy production, most transport, most industry and thereby of course make impossible all forms of space exploration. Since those political extremists always use exactly the same rethorics as this blog does on the subject, it is difficult not to identify the two of them as one and the same.

        If you blog about the climate science nowadays you need to be very clear about being against all forms of climate POLITICS. This blog never is, therefor it is rightly considered a political forum which propagates a onesided policical agenda. It’s just like blogging about racial biology in Germany in the 1930’s, you had to distinguish between politics and science to have any credibility.

        I’d rather it’d be a blog about space exploration instead.

        • jjasensio March 1, 2014, 12:17 PM

          I have a simple question: where in this entry of the blog have you seen anything about abolishing “most agticulture, most energy production, most transport, most industry”? It is speaking about a report on scientific data about the current knowledge on climate evolution. Of course not detailing the data, it is not what this blog usually does, we usually get a summary of some new scientific report.
          Then, the way to answer is to show, with other data, that: there is no increase in the concentration of CO2 and other gases, or the increase, if it exists, has other natural sources (better showiing which ones, if possible) or that, if the increase exist, it will not affect the climate (with a model as realistic at least as the models that show that there is an effect) or… the possibilities are multiple. Everybody (or almost everybody) would be very happy if it can be clearly shown.
          You know, I work in the household appliances industry. I remember, during the discussions about the Montreal Protocol on CFC´s, that it coudl affect heavily the industry I was working in, the same kind of discussion: to the data supplied by most of the scientifics, the industry and certain groups where denouncing the issue as a complot to kill the industry, which would not survive this plot. Well, the ban of CFC´s was enforced and … I guess that you still have a fridge, air condition in your car or house, etc. The World did not stop.
          This issue is larger and of course it is very important to be very careful. The data shown by the climatologist and the rest of the scientists is based on the same methods used to get data on astronomy, genetics, paleontlogy, etc. The science is the same as the one used to make iPhones, space ships or the computer I am using now. Why do most of us “believe” on this science in all cases but one?. Of course, there may be errors, wrong interpretations and even bad faith (on both sides). Look for these errors and show them. There is no lack of money on both sides to pursue the necessary investigations. See what is most probable, coming from these investigations and then, make politics.
          Well, sorry for this long answer. I will not go on. When reading this blog, enjoy the science. It is what I really like, not politics

        • joseluis March 1, 2014, 2:48 PM

          I am afraid that expressions such as “fanatic political extremists who suggest to by political force abolish most agriculture, most energy production, most transport, most industry” are indeed closer to very extreme and immoderate thinking, more than anything else that could have been said in the article or the blog.

  • joseluis March 1, 2014, 8:06 AM

    Jason: “the northern hemisphere” is much more than continental USA and Canada. I agree it has been particularly cold there this winter, but here in Europe we have had a very mild winter, at least so far. Global warming generates a more energetic atmosphere, you can expect all sorts of phenomena, including very cold weather.

  • RUF March 1, 2014, 12:47 PM

    The founder of Greenpeace recently said that there is no evidence of Man-made global warming. I’m so glad that the debate is over. It is settled science.

    • joseluis March 1, 2014, 2:58 PM

      Sure you must be kidding. Anyway, Patrick Moore left Greenpeace long ago, accusing the organization of being “leftist”? among other regrettable sins. Of course he is not alone among the global warming sceptics. The debate is still open and scientific information such as the global temperature averages in long series, as presented in this article, may help to clarify a few things.

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