Lecture 22 (Climate Change: Move to Action (Winter 2008))

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{{#if:How Do We Know That Human Activities Have Influenced Global Climate? Ben Santer. Lecture 22 is on how we determine whether or not observed climate change is due to natural variability or industrial greenhouse gases. First sources of "natural" and "non-natural" variability are described. Since we do not have the ability o run controlled experiments in the atmosphere, a strategy that uses model predictions is developed. In a model, experiments can be run that have only "natural" forcing and only "non-natural" forcing and the sum of "natural" and "non-natural." It is possible to determine "fingerprints" of different types of forcing; for instance, solar heating versus well-mixed greenhouse gas heating. Then it is required to use the observations and to determine whether the observed heating more closely resembles "natural" or "non-natural" forcing. Because of the complexity of the climate and the enormous consequences of attributing climate change to humans, it is necessary to find multiple signals. Atmospheric, oceanic, land and ice signals have been identified.

After this, a set of the "myths" about climate change is explored. Such myths are that the ocean is cooling, that models can't simulate the oceans, and that models can't simulate the observed atmospheric temperature changes. These myths are explained in terms of observations and facts. Places that require more attention are discussed.

Here is a set of my Blogs on Attribution of climate change.|== Lecture Summary == How Do We Know That Human Activities Have Influenced Global Climate? Ben Santer. Lecture 22 is on how we determine whether or not observed climate change is due to natural variability or industrial greenhouse gases. First sources of "natural" and "non-natural" variability are described. Since we do not have the ability o run controlled experiments in the atmosphere, a strategy that uses model predictions is developed. In a model, experiments can be run that have only "natural" forcing and only "non-natural" forcing and the sum of "natural" and "non-natural." It is possible to determine "fingerprints" of different types of forcing; for instance, solar heating versus well-mixed greenhouse gas heating. Then it is required to use the observations and to determine whether the observed heating more closely resembles "natural" or "non-natural" forcing. Because of the complexity of the climate and the enormous consequences of attributing climate change to humans, it is necessary to find multiple signals. Atmospheric, oceanic, land and ice signals have been identified.

After this, a set of the "myths" about climate change is explored. Such myths are that the ocean is cooling, that models can't simulate the oceans, and that models can't simulate the observed atmospheric temperature changes. These myths are explained in terms of observations and facts. Places that require more attention are discussed.

Here is a set of my Blogs on Attribution of climate change.|}} {{#if:Powerpoint Lecture 22|===Lecture Link=== Powerpoint Lecture 22|}} {{#if:* Climate Change 101

  • How do we study the causes of climate change?
  • A few common myths about climate change
  • Conclusions and some personal thoughts|===Lecture Outline===
  • Climate Change 101
  • How do we study the causes of climate change?
  • A few common myths about climate change
  • Conclusions and some personal thoughts|}}

{{#if:|== Assigned Reading == {{{Assigned Reading}}}|}} {{#if:Climate Change Science Program: Synthesis and Assessment Product: Reconciling the consistency of observed constituent trends (~9 MB)

Santer: Water vapor fingerprinting

Rosenzweig: Attribution of climate change, a physical and biological review (~ 6 MB)|== Relevant Reading == Climate Change Science Program: Synthesis and Assessment Product: Reconciling the consistency of observed constituent trends (~9 MB)

Santer: Water vapor fingerprinting

Rosenzweig: Attribution of climate change, a physical and biological review (~ 6 MB)|}} {{#if:|== Foundational References == {{{Foundational References}}}|}} {{#if:|== Relevant Readings Posted by Others == {{{Relevant Readings Posted by Others}}}|}} {{#if:Attribution, Climate Science, Guest Speakers|== Topics Covered == Attribution, Climate Science, Guest Speakers|}} {{#arraymap:Attribution, Climate Science, Guest Speakers|,|q|| }} {{#arraymap:W08|,|q|| }} {{#arraymap:Relevant|,|q|| }}



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