Chapter 2. Changes in Sea Level Melting Cryosphere Atmospheric Changes Summary IPCC (2013)

Transcription

1 IPCC (2013) Ice is melting faster (sea ice, glaciers, ice sheets, snow) Sea level is rising More ocean heat content More intense rainfall More severe drought Fewer frosts More heat waves Spring is arriving earlier 1

2 IPCC (2013) More drought Hotter days/nights increasing Colder days/nights decreasing Heavier precipitation events Stronger Hurricanes The Evidence of Climate Change (NASA link) 2

3 Sato & Hansen (2010) Web Alert: Modern Day Climate Change & Global Warming: A Sea Change Sea levels rise from thermal expansion and land-ice melt Warmer water molecules move faster so they expand Ice on land melts and the water flows into oceans 3

4 Kitchen (2013) Along shallow coastal locations such as the eastern coast of the US, vertical sea level rise corresponds to much larger horizontal movement of water inland. 4

5 Video: Climate Change & Sea Level Rise 5

6 Web Alert: Surging Seas Sea Level Rise Analysis Mapping Areas Potentially Impacted by Sea Level Rise Choose a location and map impact of future sea level rise 6

7 Video: Expecting the Unexpected: Abrupt Climate Change 7

8 Video: Stephen Colbert s The Word: Sink or Swim 8

9 Click for most recent image Web Alert: Modern Day Climate Change Arctic sea ice is decreasing in Extent (Area) Thickness (Older, thicker ice decreasing) Volume 9

10 2012 set new record minimum sea ice extent Web Alert: Click for most recent image Modern Day Climate Change Arctic sea ice is decreasing in Extent (Area) Thickness (Older, thicker ice decreasing) Volume 10

11 UK Hadley Center Web Alert: Modern Day Climate Change Arctic sea ice is decreasing in Extent (Area) Thickness (Older, thicker ice decreasing) Volume 11

12 Video: A New Climate State: Arctic Sea Ice

13 Click for most recent image Web Alert: Modern Day Climate Change Skeptical Science(2011) GRACE Rate of Mass Change Feb 2003 Feb Feb 2003 Jan Rate of ice loss in Greenland has more than doubled over the 11 year period since gravity measurements began Wahr (2014) cm/yr water thickness equivalent 13

14 Web Alert: Skeptical Science(2010) Modern Day Climate Change Antarctica losing land ice, the ice loss is accelerating at a rate of 26 Gigatonnes/yr 2 The last time Antarctica was ice free sea levels were more than 70 meters (> 200 ft) higher than present East Antarctic Ice Sheet (EAIS) is fairly stable West Antarctic Ice Sheet (WAIS) is unstable and collapse could raise sea levels 5-6 m (>15 feet) Antarctic Peninsula very unstable 14

15 Video: One Vid to Rule Them All, Part 2 15

16 UNEP/GRID (2007) Since 1900 the extent of permafrost has decreased by 15% during the warm season Decreased snow cover has exposed more permafrost to warmer temperatures Methane trapped in frozen ground is being released as ground melts. Methane is a powerful but shorter-term GHG (20x CO2, lasts for 9-15 years Positive feedback results 16

17 Video: Hunting for methane with Katey Walter Anthony 17

18 Video: Permafrost: The Tipping Time Bomb 18

19 Web Alert: World Glacier Monitoring Service (2011) Modern Day Climate Change 90-95% of worldwide glaciers are retreating (a few are gaining). 27% of sea level rise due to melting glaciers Skeptical Science (2010) 19

20 Web Alert: IPCC (2007) Modern Day Climate Change Droughts are increasing due to more evaporation in a warmer world Diffenbaugh & Ashfaq (2010) 20

21 Dai (2010) Many regions in the world, including the U.S., are forecast to have severe drought conditions in the next two decades. 21

22 Pakistan devastated by massive flood, July 2010 Wikipedia (2010) IPCC reports that intense rain events have increased in frequency during the last 50 years and human-induced global warming most likely contributed to the trend. 22

23 In the US and worldwide, extreme precipitation events are occurring more frequently in regions that are typically wet. Increased flooding is a direct result. 23

24 Web Alert: Hurricane Katrina (NOAA, 2005) Modern Day Climate Change Greenhouse warming will cause stronger storms, with intensity increases of 2 11% by 2100 Possible decreases in frequency of tropical cyclones, by 6 34% Substantial increases in the frequency of the most intense cyclones Increases of the order of 20% in the rainfall rate within 100 km of the storm center 24

25 Web Alert: Tropical cyclones in a warmer world (Pliocence) Federov, Brierley, & Emanuel (2010) Modern Day Climate Change According to NCDC, the destructive power of hurricanes has generally increased since the mid-1970s, when the period of the most rapid increase in global ocean and land temperatures began. By 2100, the climate is expected to warm 5 o C to 6 o C or more above pre-ir values. During the Pliocene, about 2.5 to 5 million years ago, CO 2 levels were comparable to today's levels (near 400 ppm) and the climate was about 3 o C to 5 o C warmer than pre-ir. Geographically, the Earth was also very similar to today so the Pliocene offers a glimpse of what the world may look like by the year

26 Web Alert: Summary of Key Points: Modern Day Climate Change 1.20 of the warmest years on record have occurred in the past 25 years. The warmest year globally was 2005 with the years 2009, 2007, 2006, 2003, 2002, and 1998 all tied for 2 nd within statistical certainty. The warmest decade has been the 2000s, and each of the past three decades has been warmer than the decade before and each set records at their end. The odds of this being a natural occurrence are estimated to be one in a billion! 2.Temperature data from 1850 to present shows that there has been an increasing trend and the rate of warming has increased rapidly in the past few decades. 3.Surface temperatures north of latitude 60 o are warming at an accelerated rate in the past few decades. 4.The Arctic was experiencing long-term cooling in the past 2000 years according to Milankovitch cycles until very recently. The cooling trend was reversed during the 20th century, with four of the five warmest decades of the 2000-year-long reconstruction occurring between 1950 and Sea ice extent has been dramatically reduced since the 1950s. 6.Since measurements began in 1953, there has been a dramatic decrease in sea ice thickness. 7.Greenland is losing ice mass and the rate is accelerating. 8.Antarctica is losing ice mass and the rate is accelerating. 9.The average mass balance of the glaciers with available long-term observation series around the world continues to decrease % of worldwide glaciers are retreating. 11.Much of the heat that is delivered by the sun is stored in the Earth's oceans while only a fraction of this heat is stored in the atmosphere. Therefore, a change in the heat stored in the ocean is a better indicator of climate change than changes in atmospheric heat. 12.The heat content of the oceans is increasing. 13.The oceans are taking in almost all of the excess heat since the 1970s which underscores the point that ocean heat content is a better indicator of global warming than atmospheric temperatures. 14.Much of this ocean heat will be vented to the atmosphere in the future thus accelerating global warming. 15.The Palmer Drought Severity Index (PDSI) curve reveals widespread increasing African drought, especially in the Sahel. 16.Global warming due to human activities is increasing the severity of drought in areas that already have drought and causing more rainfall in areas that are already wet. 17.According to the US Climate Extremes Index (CEI), extremes in climate are on the increase since The concentration of CO 2 has reached a record high relative to more than the past 500,000 years and has done so at an exceptionally fast rate. 19.Most of the warming in the past 50 years is attributable to human activities. 20.Although large climate changes have occurred in the past, there is no evidence that they took place at a faster rate than the present warming. 21.If projections of a 5 o C warming in this century are realized, Earth will have experienced the same amount of global warming as it did at the end of the last ice age. 22.There is no evidence that this rate is matched to a comparable global temperature increase over the last 50 million years! 23.Sea level gradually rose in the 20th century and is currently rising at an increased rate, after a period of little change between AD 0 and AD The trend is 50% greater than that reported by the IPCC in Sea level is predicted to rise at an even greater rate in this century, with 20th century estimates of 1.7 mm per year. 25.When climate warms, ice on land melts and flows back into the oceans raising sea levels. 26.When the oceans warm, the water expands (thermal expansion) which raises sea levels. 27.IPCC 1990 projected sea level increases were too conservative. The latest observations show that sea levels have risen faster than previous projections. 28.Greenhouse warming will cause the globally averaged intensity of tropical cyclones to shift towards stronger storms, with intensity increases of 2 11% by Substantial increases in the frequency of the most intense cyclones are expected with increases of the order of 20% in the precipitation rate within 100 km of the storm centre. 30.Rising sea-levels will result in more damage from hurricanes even if hurricane strength remains unchanged. 26