The realities of climate change in the Caribbean The use of climate models

Transcription

1 The realities of climate change in the Caribbean The use of climate models Michael A. Taylor Climate Studies Group, Mona Department of Physics University of the West Indies, Mona

2 Truth... Taylor Truth Climate change is an issue of our times, of our own doing, and of times to come. The Caribbean cannot avoid contending with it - preferably through voluntary action, now as opposed to later, and with a paradigm shift in thought and action equivalent to the shift necessitating it. Climate Change

3 CLIMATE HAS CHANGED Climate Change Distinct changes in measures of climate lasting for a long period of time Natural Volcanic Eruptions Human Activity Variations Changes in the earth s orbit Changes in solar intensity Preindustrialized era e.g. Ice Ag Alter aerosols in the atmosphere (block sunlight) not long term effect. Alter carbon dioxide concentrations (CO ) Alter aerosols in the atmosphere (block sunlight) not long term effect. Alter carbon dioxide concentrations (CO ) Changingland cover (reflective properties of earth). Altering aerosol concentrations. Post Industrial Revolution (~750). Burning of fossil fuels and biomass has altered the composition of the atmosphere primarilythroughthe addition ofgreenhouse gases.

4 CLIMATE HAS CHANGED Climate Change Distinct changes in measures of climate lasting for a long period of time CO A 6% Increase from pre-industrial times. Almost all of the increase is due to human activities (IPCC, 007). CH 4 Now 48% above pre-industrial levels. (IPCC, 007).

5 CLIMATE HAS CHANGED Climate Change Distinct changes in measures of climate lasting for a long period of time IPCC (007) It is extremely unlikely (<5%) that the global pattern of warming during the past half century can be explained without external forcing, and very unlikely that it is due to known natural external causes alone.

6 CLIMATE HAS CHANGED... TEMPERATURES IPCC: Global warming is unequivocal! There is a greater than 90 percent chance that most of the warming we have experienced since the 950s is due to the increase in greenhouse gas emissions from human activities.

7 CLIMATE HAS CHANGED... TEMPERATURES The warming trend is seen in both daily maximum (day time) and minimum (night time) temperatures. Minimum temperatures increasing at a faster rate than maximum temperatures. Land areas have tended to warm faster than ocean areas. Winter months have warmed faster than summer months.

8 CLIMATE HAS CHANGED... SEA LEVELS Primary factors driving current sea level rise include: the expansion of ocean watercaused by warmer ocean temperatures meltingof mountain glaciers and small ice caps (to a lesser extent) meltingof the Greenland Ice Sheet and the Antarctic Ice Sheet

9 CLIMATE HAS CHANGED... SEA LEVELS IPCC (007) Most of the Pacific and Atlantic basinsare experiencing average to above-average sea level rise. the rate of observed sea level rise increased from the mid 9th to the mid 0th century. During the 0th century, sea level rose at an average rate of 4.8 to 8.8 inches per century (.-. mm/year) Satellite measurements estimate that sea level has been rising at a rate of 9 to 5 inches per century (.4-.8 mm/yr) since 99.

10 CLIMATE HAS CHANGED... RAINFALL Rainfall patterns changing. IPCC (007) Significant changes in amount, intensity, frequency and type of precipitation. Trends vary widely by region and over time. Precipitation strongly modulated by variability e.g. ENSO. Globally there has been no statistically significant overall trend in precipitation over the past century.

11 CLIMATE HAS CHANGED... RAINFALL Rainfall patterns changing. IPCC (007) Precipitation has generally increased over land northof 0 N from , but has mostly declined over the tropicssince the 970s. Wetterin eastern North and South America, northern Europe and northern and central Asia, but drierin the Sahel, southern Africa, the Mediterranean and southern Asia. More precipitation now falls as rain rather than snow in northern regions.

12 CLIMATE HAS CHANGED... EXTREME RAINFALL Proportion of heavy rainfall is increasing over many land areas IPCC (007) There has been an increasein the number of heavy precipitation eventsover many areas during the past century, as well as an increase since the 970s in the prevalence of droughts especially in the tropics and subtropics. The long-term record emphasizes that patterns of precipitation vary from year to year, and even prolonged multi-year droughts are usually punctuated by a year of heavy rains; for instance as El Niño influences are felt.

13 CLIMATE HAS CHANGED... EXTREME EVENTS Tropical storm and hurricane frequencies vary considerably from year to year, but evidence suggests substantial increases in intensity and durationsince the 970s. IPCC (007) Since 950, the number of heat waves has increased and widespread increases have occurred in the numbers of warm nights. The extent of regions affected by droughtshas increasedas precipitation over land has marginally decreased. Generally, numbers of heavy daily precipitation eventsthat lead to flooding have increased, but not everywhere. In the extratropics, variations in tracks and intensity of storms reflect variations in major features of the atmospheric circulation, such as the North Atlantic Oscillation.

14 CLIMATE HAS CHANGED... AND IN THE CARIBBEAN TOO! Study done at UWI and NCDC Peterson, T. C., M. A. Taylor, et al., 00: Recent changes in climate extremes in the Caribbean region, J. Geophys. Res., 07(D) Tmax, Tmin, rainfall station data Looking if climate extremes have changed in Caribbean in recent history.

15 CLIMATE HAS CHANGED... AND IN THE CARIBBEAN TOO! Frequency of Hot days and hot nights increasing (nights > days) Frequency of cool days and nights decreasing Trendlines significant at % level Frequency of cool days and nights decreasing True for rest of world.

16 CLIMATE HAS CHANGED... AND IN THE CARIBBEAN TOO! Caribbean daily rainfall intensity decreasing Maximum number of consecutive dry days decreasing for Caribbean

17 CLIMATE HAS CHANGED... AND IN THE CARIBBEAN TOO! St. Vincent Percent number of cool days (TX90) Percent number of warm days (TX90)

18 CLIMATE HAS CHANGED... AND IN THE CARIBBEAN TOO! Farmer s perceptions in St. Elizabeth Parish from Gamble et al. (00) Farmer perceptions of increasing drought might reflect relative changes in the early (April June) and principal (August November) growing seasons. Specifically, many farmers commented in interviews that drought is becoming more prevalentin the early growing season as compared to the primary growing season. In particular, the farmers contend that the dry season before the early growing season is getting longer and the midsummer dry spell is starting sooner, in effect reducing the early growing season to one month, May.

19 CLIMATE HAS CHANGED

20 CLIMATE WILL CHANGE

21 CLIMATE WILL CHANGE... MODELS. Suppose we could guess how the concentrations of greenhouse gases will change going into the future scenarios models. Generate pictures of how the climate of the earth, or region on the earth will look in the future.. Put these concentrations in computer models that simulate all the physical processes of the earth. projections

22 CLIMATE WILL CHANGE... MODELS Models + Scenarios = Future Climate Computer simulations of future climates given conjectures of how the greenhouse gases will changegoing to the end of the century.

23 CLIMATE WILL CHANGE... CARIBBEAN MODELS In 00 a group of Caribbean climate scientists got together in Havana Cuba. Deliberate collaborative effort to produce quickly Caribbean climate projections at scale of Caribbean. Premised on shared workload to get results out quickly. Premised on building of capacity in the region. Barbados, Jamaica, Cuba, Belize, Suriname (recent)

24 CLIMATE WILL CHANGE... CARIBBEAN MODELS Models + Scenarios = Future Climate Regional Climate Model PRECIS, UK Caribbean Scale ~50 km IPCC Special Report on Emissions Scenarios i.e. SRES scenarios. Storylines associated with CO concentrations A (high emissions) and B (low emissions)

25 CLIMATE WILL CHANGE... TEMPERATURES Irrespective of scenario the Caribbean expected to warm. Warming between and 5 o C Warming greater under A scenario. Warming consistent with projections for other parts of globe. Warming far exceeds natural variability Mean changes in the annual mean surface temperature for with respect to , as simulated by PRECIS_ECH and PRECIS_Had for SRESA and SRESB.

26 CLIMATE WILL CHANGE... TEMPERATURES Irrespective of scenario the Caribbean expected to warm. Warming between and 5 o C Warming greater under A scenario. Warming consistent with projections for other parts of globe. Warming far exceeds natural variability Mean changes in the annual mean surface temperature for with respect to , as simulated by PRECIS_Had for SRESA.

27 CLIMATE WILL CHANGE... RAINFALL General tendency for drying (main Caribbean basin) by end of the century. Drying between 5% and 0% Possibly wetter far north Caribbean NDJ and FMA. Drying exceeds natural variability June-October wet season dryer! Mean changes in the annual rainfall for with respect to , as simulated by PRECIS_ECH and PRECIS_Had for SRESA and SRESB.

28 CLIMATE WILL CHANGE... RAINFALL General tendency for drying (main Caribbean basin) by end of the century. Drying between 5% and 0% Possibly wetter far north Caribbean NDJ and FMA. Drying exceeds natural variability June-October wet season dryer! Mean changes in the annual rainfall for with respect to , as simulated by PRECIS_ECH and PRECIS_Had for SRESA and SRESB.

29 CLIMATE WILL CHANGE... RAINFALL The largest precipitation signal is in June and July, in the early rainy season and the beginning of the MSD. Drying up to 5% Slide courtesy of S. Raucher

30 CLIMATE WILL CHANGE... RAINFALL Multiple uncertainties in models Consensus diagrams useful In some regions, all scenarios predict drier. In some regions all simulations predict wetter. Number of simulations projecting precipitation increase for 080s.

31 CLIMATE WILL CHANGE... GRENADA 00s 060s 090s JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANNUAL Projected temperature changes 99 through 099.

32 CLIMATE WILL CHANGE... GRENADA A B 00s 060s 090s 00s 060s 090s JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANNU AL Projected rainfall changes 99 through 099.

33 CLIMATE WILL CHANGE... SEA LEVELS Sea level will continue to risein the st century because of thermal expansion and loss of land ice. Sea level rise was not geographically uniform in the past and will not be in the future. Projected warming due to emission of greenhouse gases during the st century will continue to contribute to sea level rise for many centuries. Sea level rise due to thermal expansion and loss of mass from ice sheets would continue for centuries even if radiativeforcing were to be stabilised.

34 CLIMATE WILL CHANGE... HURRICANES Knutson et al. (008) Overall number of simulated storms in warming scenario decreases but storms that do occur tend to be more intense, with higher rainfall rates and increased maximum winds.

35 CLIMATE WILL CHANGE... HURRICANES Bender et al. (00) Overall number of simulated storms in warming scenario decreases but storms that do occur tend to be more intense, with higher rainfall rates and increased maximum winds.

36 CLIMATE WILL CHANGE... HURRICANES Hurricanesare likely to intensify in the north Atlanticwith larger peak wind speeds and more heavy precipitation due to an expected increase in sea surface temperatures. (IPCC 007)

37 CLIMATE HAS CHANGED CLIMATE WILL CHANGE

38 CLIMATE HAS CHANGED CLIMATE WILL CHANGE CLIMATE DEMANDS CHANGE

39 CLIMATE DEMANDS CHANGE. The Caribbean is climate sensitive Our lives and livelihood revolve around or are closely linked to climate. Economic: Infrastructure: Recreation Wellbeing/health E.g. Tourism, agriculture, mining, fishing E.g. Location of major cities, water quality and storage Size and topography enhances sensitivity: E.g. Hilly backbone, limited landspace, infrastructure few miles from coast.

40 CLIMATE DEMANDS CHANGE. The Caribbean is therefore vulnerable Changes in climate (short term or long term) can and do alter Caribbean existence. Droughts and floods; Hurricanes; Hot days, nights, climate change Impact felt throughout many areas of Caribbean life directly or indirectly:

41 CLIMATE DEMANDS CHANGE Recognition of our Vulnerability due to an inherent climate Sensitivityand the magnitude of the change past and to come demands a Changein how we normally operate.

42 CLIMATE DEMANDS CHANGE A Change in our Action Integrated but also Sector Specific Mitigation Actions taken by individuals or corporations to reduce the greenhouse gas emissions in order to minimize their effects on global climate change Adaptation Adjustment in natural or human systems to a new or changing environment.

43 CLIMATE DEMANDS CHANGE A Change in our Way of Thinking To respond to climate change is to pursue a path to Sustainable Development. Not an add on Not to be pursued when have money to do so Not experimental/project basis Not optional Coordinated by sector (?)

44 CLIMATE DEMANDS CHANGE Impact Sustainable Adaptation Development Agriculture Varying productivity due to floods and drought Protected agriculture Tourism Fisheries Less demand warmer world Supply less - warmer ocean rising sea levels Diversified tourism Diversification of livelihood Water Variable supply - less rainfall Efficient usage Harvesting Infrastructure Damage to coastal infrastructure - storm surge Vulnerability mapping for zoning Health More dengue - warmer temps Epidemic alert systems

45 CLIMATE DEMANDS CHANGE A Change in our Way of Thinking To respond to climate change is to pursue a path to Sustainable Development.

46 Climate Change CLIMATE HAS CLIMATE WILL CLIMATE DEMANDS CHANGED CHANGE CHANGE Taylor Truth Climate change is an issue of our times, of our own doing, and of times to come. The Caribbean cannot avoid contending with it - preferably through voluntary action, now as opposed to later, and with a paradigm shift in thought and action equivalent to the shift necessitating it.

47 Thank You