Global climate change is it real
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Global Climate Change – Is It Real?. Mac Post Oak Ridge National Laboratory Tennessee Environmental Education Association 2008 Annual Conference. CO 2 and Climate – The Basics. Atmospheric Trace Gases and Radiative Forcing of Climate

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Global Climate Change – Is It Real?

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Global climate change is it real

Global Climate Change – Is It Real?

Mac Post

Oak Ridge National Laboratory

Tennessee Environmental Education Association

2008 Annual Conference


Co 2 and climate the basics

CO2 and Climate – The Basics

  • Atmospheric Trace Gases and Radiative Forcing of Climate

  • Atmospheric CO2 concentration and the Global Carbon Cycle

  • The current human induced changes in CO2 concentration and potential for climate change


Trace gases and radiative forcing

Trace Gases and Radiative Forcing


Global climate change is it real

Greenhouse Effect


Atmospheric co 2 and the recent global carbon cycle

Atmospheric CO2 and the Recent Global Carbon Cycle


Global climate change is it real

Atmospheric CO2 and the Past Global Carbon Cycle


Human induced co 2 increase and climate change

Human Induced CO2 Increase and Climate Change

  • CO2 concentration has been relatively constant since last ice age until 1750.

  • Since 1750 CO2 has risen exponentially to an amount greater than any in the past 450,000 years.

  • CO2 is the main source of increased radiative forcing.


Conclusions

Conclusions

  • Climate change – Is it real?

    • Yes, temperatures are 0.8°C higher during the last decade than any time during the the instrumental period and the trend has been increasing for the past century.

    • there are many forces that result in climate change, and atmospheric CO2 plays a large role in all climate change.

  • Is the current climate warming the result of human fossil fuel burning?

    • Yes, in the terminology of the Intergovernmental Panel on Climate Change (IPCC) there is “high agreement” that this is true. This is equivalent to a greater than 90% certainty.


Climate skeptics top 10

Climate Skeptics’ Top 10

  • EVIDENCE THAT THE EARTH'S TEMPERATURE IS GETTING WARMER IS UNCLEAR

  • IF THE AVERAGE TEMPERATURE WAS RISING, IT HAS NOW STOPPED

  • THE EARTH HAS BEEN WARMER IN THE RECENT PAST

  • COMPUTER MODELS ARE NOT RELIABLE

  • THE ATMOSPHERE IS NOT BEHAVING AS MODELS WOULD PREDICT

  • CLIMATE IS MAINLY INFLUENCED BY THE SUN

  • A CARBON DIOXIDE RISE HAS ALWAYS COME AFTER A TEMPERATURE INCREASE NOT BEFORE

  • LONG-TERM DATA ON HURRICANES AND ARCTIC ICE IS TOO POOR TO ASSESS TRENDS

  • WATER VAPOUR IS THE MAJOR GREENHOUSE GAS; CO2 IS RELATIVELY UNIMPORTANT

  • PROBLEMS SUCH AS HIV/AIDS AND POVERTY ARE MORE PRESSING THAN CLIMATE CHANGE


Evidence that the earth s temperature is getting warmer is unclear

EVIDENCE THAT THE EARTH'S TEMPERATURE IS GETTING WARMER IS UNCLEAR

  • Warming is unequivocal. Weather stations, ocean measurements, decreases in snow cover, reductions in Arctic sea ice, longer growing seasons, balloon measurements, boreholes and satellites all show results consistent with the surface record of warming.

  • The urban heat island effect is real but small; and it has been studied and corrected for.

  • Globally, there is a warming trend of about 0.8°C since 1900, more than half of which has occurred since 1979.

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If the average temperature was rising it has now stopped

IF THE AVERAGE TEMPERATURE WAS RISING, IT HAS NOW STOPPED

  • This is always asserted by “cherry-picking” – for example:

  • 1998 was an exceptionally warm year because of the strong El Nino event. Variability from year to year is expected, if you picked 1997 or 1999 you would see a sharper rise.

  • Even so, the linear trends since 1998 are still positive.

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The earth has been warmer in the recent past

THE EARTH HAS BEEN WARMER IN THE RECENT PAST

  • There have been many periods in Earth history that were warmer than today.

  • If not the Mediaeval Warm Period, then maybe the last interglacial (125,000 years ago) or the Pliocene (three million years ago).

  • Whether those variations were caused by solar forcing, the Earth's orbital wobbles or continental configurations, none of those causes apply today.

  • Evidence for a Mediaeval Warm Period outside Europe is patchy at best, and is often not contemporary with the warmth in Europe.

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Computer models are not reliable

COMPUTER MODELS ARE NOT RELIABLE

  • Models are simply ways to quantify understanding of climate.

  • They will never be perfect and they will never be able to forecast the future exactly.

  • Models are tested and validated against all sorts of data. Over the last 20 years they have become able to simulate more physical, chemical and biological processes, and work on smaller spatial scales.

  • The 2007 IPCC report produced regional climate projections in detail that would have been impossible in its 2001 assessment.

  • All of the robust results from modeling have both theoretical and observational support.


Global climate change is it real

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The atmosphere is not behaving as models would predict

THE ATMOSPHERE IS NOT BEHAVING AS MODELS WOULD PREDICT

  • Lower levels of the troposphere are warming; but measuring the exact rate has been an uncertain process.

  • Readings from different satellites need to be tied together, and each has its own problems with orbital decay and sensor drift.

  • Two separate analyses show consistent warming, one faster than the surface and one slightly less.

  • Within the uncertainties of the data, there is no discrepancy that needs to be dealt with.

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Climate is mainly influenced by the sun

CLIMATE IS MAINLY INFLUENCED BY THE SUN

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A carbon dioxide rise has always come after a temperature increase not before

A CARBON DIOXIDE RISE HAS ALWAYS COME AFTER A TEMPERATURE INCREASE NOT BEFORE

  • This is largely true, but irrelevant.

  • Ice-cores do show CO2 rising after temperature by a few hundred years - a timescale associated with the ocean response to atmospheric changes mainly driven by wobbles in the Earth's orbit.

  • The situation today is dramatically different. The extra CO2 in the atmosphere (35% increase over pre-industrial levels) is from human emissions.

  • Levels are higher than have been seen in 650,000 years of ice-core records, and are possibly higher than any time since three million years ago.

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Long term data on hurricanes and arctic ice is too poor to assess trends

LONG-TERM DATA ON HURRICANES AND ARCTIC ICE IS TOO POOR TO ASSESS TRENDS

  • Systematic collection of data in parts of the Arctic began in the late 18th Century.

  • The US National Hurricane Center notes that "organised reconnaissance" for Atlantic storms began in 1944.

  • So although historical data is not as complete as one might like, conclusions can be drawn.

  • The IPCC does not claim that global warming will make hurricanes more frequent - its 2007 report says that if anything, they are likely to become less frequent, but more intense.

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Water vapour is the major greenhouse gas co 2 is relatively unimportant

WATER VAPOUR IS THE MAJOR GREENHOUSE GAS; CO2 IS RELATIVELY UNIMPORTANT

  • The statement that water vapor is "98% of the greenhouse effect" is simply false. In fact, it does about 50% of the work; clouds add another 25%, with CO2 and the other greenhouse gases contributing the remaining quarter.

  • Water vapor is essentially in balance with the planet's temperature on annual timescales and longer, whereas trace greenhouse gases such as CO2 stay in the atmosphere on a timescale of decades to centuries.

  • Absorption at H2O wavelengths is already saturated so increases have little effect.

  • Water vapor is a feedback is included in all climate models.

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Problems such as hiv aids and poverty are more pressing than climate change

PROBLEMS SUCH AS HIV/AIDS AND POVERTY ARE MORE PRESSING THAN CLIMATE CHANGE

  • The latest IPCC Working Group 2 report suggests that the impact of man-made climate change will on balance be deleterious, particular to the poorer countries of the tropics.

  • Investment in energy efficiency, new energy technologies and renewables are likely to benefit the developing world.

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