Climate change 2013 – Key science points from the 2013 "Intergovernmental Panel on Climate Change" report


These key science points were published on September 27, 2013, as “headline statements” by the Intergovernmental Panel on Climate Change (IPCC) as part of the organization’s fifth assessment report. Background links are provided by Earth Observatory.

  • Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased. Read more about global warming.
  • Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850. In the Northern Hemisphere, 1983–2012 was likely the warmest 30-year period of the last 1400 years. See maps showing global temperature trends.
  • Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010 (high confidence). It is virtually certain that the upper ocean (0−700 m) warmed from 1971 to 2010, and it likely warmed between the 1870s and 1971.Read more about Earth’s energy budget.
  • Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent (high confidence). Read more about Arctic and Antarctic sea ice.
  • The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia (high confidence). Over the period 1901–2010, global mean sea level rose by 0.19 [0.17 to 0.21] m. Read more about sea level rise.
  • The atmospheric concentrations of carbon dioxide (CO2), methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years. CO2 concentrations have increased by 40% since pre-industrial times, primarily from fossil fuel emissions and secondarily from net land use change emissions. The ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification. Read more about the greenhouse effect.
  • Total radiative forcing is positive, and has led to an uptake of energy by the climate system. The largest contribution to total radiative forcing is caused by the increase in the atmospheric concentration of CO2 since 1750. Read more about radiative forcing.
  • Human influence on the climate system is clear. This is evident from the increasing greenhouse gas concentrations in the atmosphere, positive radiative forcing, observed warming, and understanding of the climate system. Read more about the human fingerprint on the climate system.
  • Climate models have improved since the AR4. Models reproduce observed continental-scale surface temperature patterns and trends over many decades, including the more rapid warming since the mid-20th century and the cooling immediately following large volcanic eruptions (very high confidence). Read more about climate models.
  • Observational and model studies of temperature change, climate feedbacks and changes in the Earth’s energy budget together provide confidence in the magnitude of global warming in response to past and future forcing. Read more about Earth’s energy budget.
  • Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes. This evidence for human influence has grown since AR4. It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. Read more about the human influence on climate.
  • Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions. Read more about greenhouse gases. 
  • Global surface temperature change for the end of the 21st century is likely to exceed 1.5°C relative to 1850 to 1900 for all RCP scenarios except RCP2.6. It is likely to exceed 2°C for RCP6.0 and RCP8.5, and more likely than not to exceed 2°C for RCP4.5. Read more about global surface temperatures.
  • Warming will continue beyond 2100 under all RCP scenarios except RCP2.6. Warming will continue to exhibit interannual-to-decadal variability and will not be regionally uniform. Read more about the NASA GISS tempearture record.
  • Changes in the global water cycle in response to the warming over the 21st century will not be uniform. The contrast in precipitation between wet and dry regions and between wet and dry seasons will increase, although there may be regional exceptions. Read more about the water cycle.
  • The global ocean will continue to warm during the 21st century. Heat will penetrate from the surface to the deep ocean and affect ocean circulation. Read more about how oceans absorb heat.
  • It is very likely that the Arctic sea ice cover will continue to shrink and thin and that Northern Hemisphere spring snow cover will decrease during the 21st century as global mean surface temperature rises. Global glacier volume will further decrease. Read more about sea ice.
  • Global mean sea level will continue to rise during the 21st century. Under all RCP scenarios the rate of sea level rise will very likely exceed that observed during 1971–2010 due to increased ocean warming and increased loss of mass from glaciers and ice sheets. Read more about sea surface temperature.
  • Climate change will affect carbon cycle processes in a way that will exacerbate the increase of CO2 in the atmosphere (high confidence). Further uptake of carbon by the ocean will increase ocean acidification. Read more about the ocean’s carbon balance.
  • Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond. Most aspects of climate change will persist for many centuries even if emissions of CO2 are stopped. This represents a substantial multi-century climate change commitment created by past, present and future emissions of CO2. Read more about carbon dioxide.

Source: Earth Observatory

Featured image: NASA Earth Observatory image by Robert Simmon, using Suomi NPP VIIRS data provided courtesy of Chris Elvidge (NOAA National Geophysical Data Center).

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  1. Thankyou for publishing this excellent summary of the IPCC report. The science is settled. t is now time to get on with reducing/eliminating emissions.

    We need to shut down the coal industry over the next 10 years and replace oil/coal/gas as our energy source with wind/solar/geothermal/hydro.

    Lets get on with it.

  2. What you should think about this report?
    1. ENJOY life! Enjoy the planet!
    Don't feel guilty about ‘carbon footprints’.
    CO2 is the Gas Of Life (GOL)! More GOL increases plant & animal life.
    2. Accept Man can’t change Climate!
    The Problem is Climate Change POLICY. ‘Climate Science’ lacks integrity. Prove &
    predict! Standards of science must apply to Climate.
    3. STOP Carbon reductions, Carbon tax & Trading
    NO PRAYER WHELLS (Wind farms)
    MONEY BACK on Green Electricity Charges – Theft
    Your electricity bill has gone up 25% for the Green Con and is set to double
    4. KEEP honest green policies to reduce smoke & chemical
    pollution and defend biodiversity.
    5. USE LONG RANGE Scientific Solar-Lunar Weather Forecasts &
    Prepare for the developing Mini Ice Age

  3. Lookit the denialists and their weak objections:

    o scientists iz munny-grubbin!

    o Algore is fat!

    o Richard Lindzen said…

    This lame talking point stew is the best they can do. Denialists have no power or influence, and their nincompoopery is meaningless. The only thing holding back climate action is the will of the plutocrats.



  4. I agree with most of the comments that this is a set up by NASA and the Cabal. And they are not reporting on the CHEMTRAILS and HAARP in which they are using to modify weather changes and even create them. It is called Geo-engineering. And that is the real deadly stuff cause the are not only modifying the Weather but they are killing off the plant and animal life and of course us humans.

    What is not dead or dying has become very sick, I am sick now for the 1000th time from the CHEM-TRAILS. Now they want us to believe that we are doing it and not them, so they can TAX the very air we have left to breath and use this carbon Tax $ along with the PHARM industry money they get from us buying there deadly Drugs struggling to stay alive so we can continue to be there Slaves in the NWO the Cabal has set up.
    Yes there are Earth changes happening and there is also Dimensional Changes happening. They know they can't go to the higher 4D and 5D with us so they are trying to keep us here in the 3D Hell that they have created. Sorry my web site is down to purchase my free books but I am posting blogs about this on the; Ashtar command Adonai,Rev. Joshua Skirvin,

  5. Environmentalists' entire livelihood depends on the prediction of continuous climatic catastrophes, regardless of how accurate they turn out to be. And, it pays a lot better than being a greeter at WalMart.

  6. According to all the climate models, which form the basis of the most recent IPCC report, storm activity is increasing along with the severity of the storms. Al Gore is predicting, again using the climate models, the end of civilization by the end of the century. What most of us deniers can't understand is why the facts keep contradicting the climate models and Al Gore. Perhaps we are not the deniers after all

  7. Lindzen, a top climate scientist from the Massachusetts Institute of Technology lambasted a new report from the UN’s climate bureaucracy that blames mankind as the main cause of global warming while whitewashing the fact that there has been no warming for the last 15 years.

    “They are proclaiming increased confidence in their models as the discrepancies between their models and observations increase,” said Lindzen.

    The IPCC claimed it was 95 percent sure that global warming was mainly driven by humans. It also glossed over the fact that the Earth has not warmed in the past 15 years.

    “Their excuse for the absence of warming over the past 17 years is that the heat is hiding in the deep ocean,” Lindzen said. “However, this is simply an admission that the models fail to simulate the exchanges of heat between the surface layers and the deeper oceans.”

    “They now, somewhat obscurely, admit that their crucial assumption was totally unjustified.”

    Governments have been urging scientists to cover up the fact that temperatures have not been rising. Germany, Belgium, Hungary, even the United States, have pressured UN climate scientists to downplay or even omit data that shows the world hasn’t warmed in over a decade

    “It is quite amazing to see the contortions the IPCC has to go through in order to keep the international climate agenda going,” says Lindzen.

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