Global Climate Change Earth is Warming How do

Global Climate Change • Earth is Warming • How do we know? • What do we know? • How confident are hypotheses about causes? • What are greenhouse gases? • Where do they come from, and how do we know? • Most common claims of the skeptics • T’s are going down, not up • This warming is just part of a natural cycle • CO 2 is good for plants

NOAA Global Historical Climatology Network: DATA Stations with at least 10 years of record for these 30 -yr intervals http: //www. ncdc. noaa. gov/oa/climate/ghcn-daily/

The Historical T Data Network From: Kitchen (2014) – Global Climate Change

Anomalies instead of Absolute T Data 1. Variations from station to station can be erratic due to small variations in local conditions 2. Regional anomalies are much more consistent, over a larger area, than station to station readings. 3. Anomalies allow more accurate assessment of T variation through time.

Days vs. Nights From: Kitchen (2014) – Global Climate Change

IPCC - Data IPCC - 2007

IPCC – Last 2000 yrs IPCC- 2007

Land + Ocean T’s National Research Council (2010) – weather stations + SST’s from direct and satellite measurements.

Melting Ice Greenland Jakobshavn is the fastest-flowing glacier in the world. In 2010, the glacier moved at 15 kilometers per year, shedding ice into the Arctic Ocean as it surged from land to sea. It drains more than six percent of the Greenland ice cap and contributes more to global sea level rise than any other feature in the Northern Hemisphere. The glacier has both retreated and thinned in recent years. In 2010, Jakobshavnretreated 1. 5 kilometers. Antarctica Two weeks after a new record was set in the Arctic Ocean for the least amount of sea ice coverage in the satellite record, the ice surrounding Antarctica reached its annual winter maximum—and set a record for a new high. Sea ice extended over 19. 44 million square kilometers (7. 51 million square miles) in 2012, according to the National Snow and Ice Data Center (NSIDC). The previous record of 19. 39 million kilometers (7. 49 million square miles) was set in 2006. http: //visibleearth. nasa. gov/view. php? id=76590 http: //earthobservatory. nasa. gov/I OTD/view. php? id=79369&src=ve

From: Kitchen (2014) – Global Climate Change

Arctic Sea Ice http: //earthobservatory. nasa. gov/Features/World. Of. Change/sea _ice. php National Snow and Ice Data Center (NSIDC) Over the last decade, Arctic sea ice extents in September have set record lows three times, and the 2011 minimum nearly tied the 2007 record low. “The nine lowest maximum extents have occurred in the last nine years, since 2004, ” Meier says.

Warming + Melting = Sea Level Rise From: Kitchen (2014) – Global Climate Change

Global Climate Change • Earth is Warming • How do we know? • What do we know? • How confident are hypotheses about causes? • What are greenhouse gases? • Where do they come from, and how do we know? • Most common claims of the skeptics • T’s are going down, not up • This warming is just part of a natural cycle • CO 2 is good for plants

Causes of Warming – How confident? Visible light Shorter wavelengths and higher energy Wavelengths (not to scale) Gamma rays X rays 0. 001 0. 1 1 Nanometers UV radiation 10 0. 1 Infrared radiation 10 Micrometers Microwaves TV, Radio waves 100 0. 1 1 10 100 Centimeters Meters Longer wavelengths and lower energy Electromagnetic Spectrum: light = energy = waves

Flow of Energy to and from the Earth Solar radiation Radiated by atmosphere as heat Reflected by atmosphere UV radiation Most UV absorbed by ozone Lower Stratosphere (ozone layer) Visible light Troposphere Heat added to troposphere Heat radiated by the earth Greenhouse effect Absorbed by the earth From: Miller (2010) Living in the Environment

What’s a Greenhouse Gas? • Greenhouse gases respond to long-wave radiation (infrared radiation) by ‘vibrating’ – this vibration sends out (or re-radiates) a portion of that original infrared radiation – heat. • Some of these are: • Water vapor • Carbon dioxide • Methane • CFCs • Ozone

Yellow = observed by satellites Valleys = absorption by GHG’s CO 2 could raise overall heat budget of atmos. by 3%

National Research Council - GHG Analysis of air bubbles trapped in Antarctic ice cores show that, along with carbon dioxide, atmospheric concentrations of methane (CH 4) and nitrous oxide (N 2 O) were relatively constant until they started to rise in the Industrial era. Atmospheric concentration units indicate the number of molecules of the greenhouse gas per million molecules of air for carbon dioxide and nitrous oxide, and per billion molecules of air for methane. Source: U. S. Global Climate Research Prog.

How Do We Know We’re Adding CO 2 to the Atmosphere? 14 C! • Living things incorporate 14 C into their bodies in the same proportion as it occurs in the atmosphere • When the organism dies, it begins to lose 14 C, via radioactive decay [half-life of 5730 yrs] • Tree rings record relative amounts of 14 C in the atmosphere, and show a large increase in the proportion of 12 C since the industrial revolution • This comes from fossil fuels, which are too old to have any 14 C remaining

Carbon dioxide in atmosphere Carbon Cycle Respiration Photosynthesis Animals (consumers) Diffusion Burning fossil fuels Forest fires Plants (producers) Deforestation Transportation Respiration Carbon in plants (producers) Carbon dioxide dissolved in ocean Carbon in animals (consumers) Decomposition Marine food webs Producers, consumers, decomposers Carbon in limestone or dolomite sediments Carbon in fossil fuels Compaction Process Reservoir Pathway affected by humans Natural pathway Fig. 3 -19, p. 70

Trends in CO 2 : NOAA http: //www. esrl. noaa. gov/gmd/ccgg/trends/history. html

Temperature and CO 2 Temperature change (blue) and carbon dioxide change (red) observed in ice core records Many other records are available

Temperature and CO 2 An estimate from the tropical ocean, far from the influence of ice sheets, indicates that the tropical ocean may warm 5°C for a doubling of carbon dioxide. The paleo data provide a valuable independent check on the sensitivity of climate models, and the 5°C value is consistent with many of the current coupled climate models.

Temperature Projections - NOAA http: //www. climate. gov/#education/teaching. Resources

Global Climate Change • Earth is Warming • How do we know? • What do we know? • How confident are hypotheses about causes? • What are greenhouse gases? • Where do they come from, and how do we know? • Most common claims of the skeptics • T’s are going down, not up • This warming is just part of a natural cycle • CO 2 is good for plants