# Presentation: 910307

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*NOAA 31st Climate Diagnostics and Prediction Workshop*
*Boulder, Colorado*
*October 25 2006*

**Challenges in Attribution of Climate Variability and Trends**

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***     ******Popular Views On Attribution***

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***     ******Popular Views On Attribution***

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***     ******Popular Views On Attribution***

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***                                             ******What is Attribution?***
**Attribution is the action of ascribing a known condition to a particular source or sources.  **
**Attribution is the process of establishing cause and effect. **
**Attribution science involves the comprehensive explanation of current and evolving **
**   ****climate conditions...both variability and change, **
**Attribution seeks to explain the role of forcings...both natural and anthropogenic. **
**Attribution includes the explanation of climate predictions...their success and failure.**

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***                                      ******Why is Attribution Important?***

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***                                      ******Why is Attribution Important?***

-        ***In Spring 2006, the Senate Commerce ***
***Disaster Prevention and Prediction Subcommittee ***
***requested NOAA to explain the very warm and***
***      ******evolving drought conditions in the West.***

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***                                      ******Why is Attribution Important?***

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***                                      ******Why is Attribution Important?***

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***                                      ******Why is Attribution Important?***

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***                                      ******Why is Attribution Important?***

-     ***US House Committee on Science***
***met  7 October 2005 to have NOAA***
***  ***_***explain***_*** its prediction of hurricanes.***

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***           ******Current Attribution Challenges***
-   ***Why has there been a recent increase in Atlantic hurricane activity?***

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***           ******Current Attribution Challenges***
-   ***Why has there been a recent increase in Atlantic hurricane activity?***

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***      ******Current Attribution Challenges***
*** ******How do we explain the 2006 hurricane predictions?***

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***           ******Current Attribution Challenges***
*** ******How do we explain the 2006 hurricane predictions?***

**Predictions of tropical activity in the 2006 season**
- Source	Date	         Named storms	Hurricanes	Major hurricanes
- CSU	A*verage (1950–0) *      9.6	5.9	2.3
- NOAA	A*verage*	                   10	  6	 2
- R*ecord high activity**	**                   *28	15	 8
- R*ecord low activity**	**                     *4	2	 0
- CSU	5 December 2005	17	9	5
- CSU	4 April 2006	17	9	5
- NOAA	22 May 2006	13–16	8–10	4–6
- CSU	31 May 2006	17	 9	5
- CSU	3 August 2006	15	 7	 3
- NOAA	8 August 2006	12–15	7–9	3–4
- CSU	1 September 2006	13	 5	2
- CSU	3 October 2006	11	 6	2
_**Activity to date**_	                      ***9***	   ***5***	  ***2***

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***                    ******Current Attribution Challenges***
*** ******How do we explain the regionality and the seasonality of US sfcT trends ?***

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***                    ******Current Attribution Challenges***
*** ******How do we explain the regionality and the seasonality of US sfcT trends ?***

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***                    ******Current Attribution Challenges***
*** ******How do we explain the regionality and the seasonality of US sfcT trends ?***

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***           ******Current Attribution Challenges***
***       ******How do we explain the long-lead seasonal outlooks?***

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***           ******Current Attribution Challenges***
***       ******How do we explain the long-lead seasonal outlooks?***

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***        ******Current Attribution Challenges***
***  ******Is the risk of drought now increasing, and if so, why?***

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**Areal-Coverage of PDSI<-3**

**Average Duration of PDSI<-3**

**Drought Statistics:  1895-1950**

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**Drought Statistics:  1951-2005**

**Areal-Coverage of PDSI<-3**

**Average Duration of PDSI<-3**

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-  **Explaining Changes in Extreme US Climate Events.......*****Jerry Meehl***
** ****Explaining US Precipitation and Temperature Trends....*****Imke Durre***
** ****Explaining Origins of North American Drought.............*****Richard Seager***
** ****Explaining Increases in Atlantic Hurricane Activity......*****Kevin Trenberth***

_**Overarching Challenge:**_
***Given the public perception of climate change and an increase in extreme events ***
***(e.g. droughts, heat waves, hurricanes), how well is our science community positioned ***
***to provide critical decision support information  (e.g., answer to  the questions ***
***what happened, why it happened, and what is likely to happen next)***
***needed for planners to  make decisions and manage risk?***

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_**Overarching Challenge:**_
***Given the public perception of climate change and an increase in extreme events ***
***(e.g. droughts, heat waves, hurricanes), how well is our science community positioned ***
***to provide critical decision support information  (e.g., answer to  the questions ***
***what happened, why it happened, and what is likely to happen next)***
***needed for planners to  make decisions and manage risk?***
***Q1      *****What attribution questions are of high relevance to decision makers,**
**                ****e.g., in water resources planning, agriculture, energy, and policy making **
**for sustainable development?**

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_**Overarching Challenge:**_
***Given the public perception of climate change and an increase in extreme events ***
***(e.g. droughts, heat waves, hurricanes), how well is our science community positioned ***
***to provide critical decision support information  (e.g., answer to  the questions ***
***what happened, why it happened, and what is likely to happen next)***
***needed for planners to  make decisions and manage risk?***
***Q2     *****What is the contribution of **_**natural variability**_** **
**to the U.S. warming since 1970s?**

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_**Overarching Challenge:**_
***Given the public perception of climate change and an increase in extreme events ***
***(e.g. droughts, heat waves, hurricanes), how well is our science community positioned ***
***to provide critical decision support information  (e.g., answer to  the questions ***
***what happened, why it happened, and what is likely to happen next)***
***needed for planners to  make decisions and manage risk?***
***Q3  *****What is the explanation for **_**regionality and seasonality**_** of US temperature**
**trends since the 1970s?**

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_**Overarching Challenge:**_
***Given the public perception of climate change and an increase in extreme events ***
***(e.g. droughts, heat waves, hurricanes), how well is our science community positioned ***
***to provide critical decision support information  (e.g., answer to  the questions ***
***what happened, why it happened, and what is likely to happen next)***
***needed for planners to  make decisions and manage risk?***
***Q4  *****What is the documented evidence for trends in **_**climate extremes**_** over the US?**

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_**Overarching Challenge:**_
***Given the public perception of climate change and an increase in extreme events ***
***(e.g. droughts, heat waves, hurricanes), how well is our science community positioned ***
***to provide critical decision support information  (e.g., answer to  the questions ***
***what happened, why it happened, and what is likely to happen next)***
***needed for planners to  make decisions and manage risk?***
***Q5  *****How do we explain the **_**successes and failures**_** of individual climate forecasts?**

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_**Overarching Challenge:**_
***Given the public perception of climate change and an increase in extreme events ***
***(e.g. droughts, heat waves, hurricanes), how well is our science community positioned ***
***to provide critical decision support information  (e.g., answer to  the questions ***
***what happened, why it happened, and what is likely to happen next)***
***needed for planners to  make decisions and manage risk?***
***Q5  What is the reason for the ***_***controversy***_*** in explaining Atlantic Hurricane variability? ***