Presentation on theme: "Oceans and Climate Change: What We Think We Know"— Presentation transcript:
1 Oceans and Climate Change: What We Think We Know Dr. John T. EverettProject Manager, United Nations Atlas of the OceansFormer IPCC Convening Lead Author (SAR) - FisheriesFormer Director, Division of Research, NOAA/NMFSOcean AssociatesOceans and Fisheries Consulting4007 North Abingdon StreetArlington, Virginia, USA
2 This PresentationIs based largely on the IPCC 1995 Report; Fisheries - Chapter 16. It is valid and best availableThe 2001 IPCC report of impacts is by region. There is little information specifically on marine fisheriesThe 2001 US National Assessment does not treat marine fisheries in depth (USNA)Physical changes reflect the 2001 IPCC report (IPCC 2001)
3 Intergovernmental Panel on CC Mission: provide an authoritative statement of scientific opinion on CCBroadly peer reviewed plus govm’t reviewSeveral hundred scientists serve on WG’sscience of climate change itselfimpacts and response strategiesbroad socioeconomic issues
4 Fisheries Lead Authors Dr. John T. Everett, CLA Dr. Daniel Lluch BeldaWashington, USA La Paz, BCS, MexicoDr. Andre Krovnin Dr. Henry A. RegierMoscow, Russia Toronto, CanadaDr. Ezekiel Okemwa Jean-Paul TroadecMombasa, Kenya Brest, France
6 Physical Changes Climate change will come with changes in temperature, circulation,sea level,ice coverage,wave climate, andextreme events,Affecting ecosystem structure & function
7 TemperatureObs: 1998 was hottest year in “Global average land and ocean temperature was the warmest on record for January (NOAA CDC 2002)”Proj: Ave. temp. to increase ° C by 2100High n. latitudes warm more than averageNights (2X) & winters warm more than averageOcean changes lag land by 10 yearsExceptions: delay or cooling in belt around Antarctica and in high N. AtlanticIn high latitudes, the growing period and productivity should increase
8 Temperatures are Rising - Recently Source: IPCC 2001
11 7 of 9 Models Agree on Warmer Winters & Summers in Northeast Source: IPCC 2001
12 Currents & UpwellingProj: A weakening of the global thermo-haline circulation may occur, reducing heat transport to the N. AtlanticCompeting arguments on oceanic & coastal upwelling increase or decreaseNo reliable forecastsForces driving natural variability not well understoodCurrents and upwelling. Freshwater influx from the movements and melting of sea ice or ice sheets may lead to a weakening of the global thermohaline circulation, leading to cooling in the North Atlantic and possibly causing unpredictable instabilities in the climate system. There are competing arguments as to whether oceanic and coastal upwelling would increase or decrease. In any case, there is no ability to make reliable forecasts at the regional scale which governs the upwelling systems. Forces leading the oceans to vary in temperature and currents on decadal scales of natural variability are not well understood and are not well modelled.
13 Ocean Conveyer BeltSource: US National Assessment
14 Storms and El NiñoObs: No trends in storminess in last 50 years. Some regional trends in storminess in both directionsThe post 1989 period of ENSO activity seems unusually high, but may have happened beforeProj: Changes in frequency & intensity of cyclones, storms, & El Niño uncertain
15 Ice CoverObs: Two weeks less fresh ice in last ~125 yrs. No evident trend in sea ice in Antarctic.Proj: Glaciers and snow and ice coverage to continue retreat in N. hemisphere. Major loss of fresh & sea iceThe NW Passage & N. Sea Route of Russia may have 100 days of shipping. 40% thinner summer Arctic ice since ~1960In the Antarctic, the main effect will be a retreat of the ice edgeIce coverage impacts ice-associated species, primary productivity, fishing and aquaculture
16 Sea Level RiseObs. show cm. rise since 1900; 1-2 mm/yr. 10X faster than previous 3K yrs. No acceleration detectedProj. is cm by 2100; from thermal expansion & melting of ice. USNA*: +19” by 2100Regional variations due to wind and atmospheric pressure, ocean density, land motion, currentsW