# Presentation: 049588

**Using Paleotempestology in Support of Decision-making Under Uncertainty of Hurricane Climate Variability***** ***
**Kam-biu Liu**
**Louisiana State University**

## What is Paleotempestology ?

- <date/time>

**What is Paleotempestology ?**

- “Paleotempestology is a new field of science that studies past hurricane activities by means of geological and archival techniques” (Liu, 2004)

- Coastal lake-sediment record of past hurricane strikes

**Homer Pond, Cape Cod**

## Paleotempestology

_**Paleotempestology**_
- 	 Principles:
- 	 Methods:
- 	 Applications:
- 	      Users:

## Why Study the Past? 

_**Why Study the Past?**_
-  Historical hurricane record only goes back 150 years.
** **A long-term perspective is essential in determining the return period of the “Big Ones” (cat 4-5 catastrophic hurricanes).
** **Are these 50-year events or 500-year events ?

- Category 4 & 5 hurricanes are extremely rare

## Multi-decadal variability

**Multi-decadal variability**

- 1947-1969

- 1970-1987

- ** Are there bigger cycles superimposed on these multi-decadal cycles?

## In a nutshell .... 

**Paleotempestology can be used to define and quantity the ****uncertainty**** about hurricane risk by generating long-term records of catastrophic hurricane strikes that encompass a much wider range of variability than that contained in the historical record of the last 150 years.**
**Areas of uncertainty:**
**Return period**
**Temporal variability**
**Spatial variability**
**Worst-case scenario**
**Future climate change and variability**

## Uncertainties about Hurricane Risk

- What is the probability for any specific place on the U.S. coasts to be directly hit by a catastrophic hurricane of category 4 or 5 intensity?
- How does this landfall probability vary temporally, and at what timescales?
-  Do hurricane activities vary from one century (millennium) to the next?
- What about spatial variability along Gulf vs East Coast?
-  What controls hurricane tracks and landfall locations?
- Are the 1940s to 1960s worst case scenario?  If not, how bad can it be?
- How are these long-term changes in spatial and temporal patterns related to global climate changes?

## Paleotempestology Study Sites

- <date/time>

***Belize***

***Honduras***

***Jamaica***

***Turks & Caicos***

- U.S. Gulf coast and Atlantic coast

- Caribbean region

**Paleotempestology Study Sites**

- There are fewer than ten well-dated, well-validated proxy records on the U.S. Gulf coast and Atlantic coast.
- Large data gaps exist.
- Need more “paleo-weather stations” !

- <date/time>

- Return period for catastrophic hurricanes = 300 yr
- Millennial-scale variability
- Hyperactive period 3400-1000 yr ago

- <date/time>

**The Bermuda High Hypothesis**

- Bermuda High provides the steering mechanism that determines hurricane tracks
- A southwestward shift of the Bermuda High at 3400 BP steered more hurricanes towards Gulf coast
- Implication:  Hurricane activities along the Gulf coast and Atlantic coast should be negatively correlated (anti-phase pattern)

## Data support the hypothesis that hurricane activities along the Gulf Coast and Atlantic Coast are in a see-saw (anti-phase) pattern controlled by the Bermuda High.

- U.S. East Coast is in the active phase in the long-term hurricane activity cycle.

-   **Spatial and Temporal**
**  ****Variability:**
-  Gulf Coast vs Atlantic Coast

## ?

- <date/time>

**Is there a link between hurricane and fire ?**

**?**

- _Hypothesis of hurricane-fire interactions_:   Fire hazard increases significantly after a major hurricane strike due to fuel accumulation (dead biomass).

## Increased hurricane activity also means increased fire risk

- <date/time>

- Ivan’s ecological impacts:  massive tree mortality

- Occurrence of charcoal peaks above sand layers indicates catastrophic wildfires after major hurricane strikes.

## Lessons Learned from Paleotempestology

- Paleotempestology helps us understand the climate mechanisms controlling hurricane activities (e.g., Bermuda High & storm tracks)
- For Gulf coast locations, catastrophic hurricanes (cat 4-5) have a return period of ca. 300 years (*p* = 0.3%/yr)
- For the Gulf coast, the past millennium is in the low-activity phase of the mega-cycle of hurricane activity.  (*we haven’t seen anything yet!*)
- If the climate regime characteristic of the “hyperactive period” returns in the future, hurricane landfall probability for the Gulf coast may increase by 3-5 times (upper limit of hurricane risk).

## Paleotempestology – Implications for Decision-making

**Hong Kong**

**Paleotempestology – Implications for Decision-making**
- 100-billion-dollar question:  *What is the probability for any U.S. coastal location to be directly hit by a catastrophic hurricane?*
- How would a worst-case scenario of a quadrupled hurricane risk impact the insurance industry, real estate market, population growth, and migration pattern of a coastal region?
- In rebuilding New Orleans, should we construct a levee system that can only withstand a category 3 hurricane?
- Regional planning; building codes; real estate values; tourism
- Disaster management and Emergency response
- Future:  Sea-level rise and global warming; coastal communities

## Pressing Issues in Paleotempestology

- _Barriers_:
- Need to inform public (decision-makers) on need for long-term perspective (outreach)
- Need more funding to support both basic science and applications
- _Information needs_:
- Need more well-dated, well-validated records (“paleo-weather stations”) from data gaps
- Caribbean region
- _Research priorities_:
- Increase regional data networks
- Use modern analogs (e.g., Ivan, Katrina) to calibrate proxy records
- Encourage paleoclimate model-data comparison
- Development of multiple proxies
- _Communications_:
- Improve communications with stakeholders, e.g., Corps of Engineers, FEMA, risk managers
- Increase collaboration & partnership among scientists, industry, & government
- Increase collaboration between paleotempestologists & decision/social scientists
- Increase multi- and cross-disciplinary collaboration