Schematic framework of anthropogenic climate change drivers, impacts and responses to climate change, and their linkages (IPCC, 2007).

Warming of the climate system is unequivocal, as is evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level (IPCC, 2007).

NASA scientists say 2012 and 2013 were the 9 th and 4 th warmest years on Earth since 1880, continuing a long-term trend of rising global temperatures. With the exception of 1998, the nine warmest years in the 132-year record all have occurred since 2000, with 2010 and 2005 ranking as the hottest years on record the hottest year on record in U.S. (U.S. only comprise 2% of globe)!

Changes in physical and biological systems and surface temperature (IPCC, 2007). Of the 29,000 observational data series from 75 studies, that show significant change in many physical and biological systems, more than 89% are consistent with the direction of change expected as a response to warming (IPCC, 2007).

Global carbon dioxide production by country. Note that China surpassed the U.S. production three years ago and India and Brazil are rapidly developing!

Relative importance of atmospheric gases and particulate matter on global warming versus cooling. Note that methane gas has a greater greenhouse effect than CO 2 gas, but its anthropogenic productioin and overall atmospheric level is lower.

(a) Global annual emissions of anthropogenic GHGs (greenhouse gases) from 1970 to (b) Share of different anthropogenic GHGs in total emissions in 2004 in terms of CO 2 -eq. (c) Share of different sectors in total anthropogenic GHG emissions in 2004 in terms of CO 2 -eq. (forestry includes deforestation) (IPCC, 2007).

(a) Distribution of regional per capita GHG emissions according to the population of different country groupings in (b) Distribution of regional GHG emissions per US$ over the GDP of different country groupings in The percentages in the bars in both panels indicate a region’s share in global GHG emissions. (IPCC, 2007).

Anthropogenic concentrations of CO 2, CH 4 and N 2 O) over the last 10,000 years (large panels) and since 1750 (inset panels). Measurements are shown from ice cores (symbols with different colors for different studies) and atmospheric samples (red lines). The corresponding radiative forcings relative to 1750 are shown on the right hand axes of the large panel (IPCC, 2007). The atmospheric concentrations of CO 2 and CH 4 in 2005 exceed by far the natural range over the past 650,000 years.

How is the rate of atmospheric CO 2 concentration changing over time? What accounts for the annual variation in the Mauna Loa record?

Dissolved CO 2 content of the world’s oceans follows the trend of the rise in atmospheric CO 2 content. As dissolved CO 2 content increases in the world’s oceans, pH decreases (acidity increases).

Global average radiative forcing (RF) in 2005 with respect to 1750 for CO2, CH4 and N2O and other important agents and mechanisms (IPCC, 2007).

A climate model could be defined as a mathematical representation of the climate system based on physical, biological and chemical principles. What is a climate model?

General Circulation Models (GCMs) try to account for all the important properties of the system at the highest affordable resolution. Simple climate models (such as the Energy Balance Models, or EBMs) propose a highly simplified version of the dynamic of the climate system. EMICs (Earth Models of Intermediate Complexity) are located between those two extremes.

CLIMAP Member, 1976 (Published in the journal Science) Boundary Conditions Used in the GCM Simulations of the LGM (18,000 years ago) Atmosphere 1. Geography of the continents 2. The albedo of the land and ice surfaces 3. The extent and elevation of permanent ice 4.The sea-surface temperature The numerical simulations will serve to evaluate the sensitivity of the GCM substantial changes in the boundary conditions and to elucidate the dynamics of the past climates.

CLIMAP reconstruction of SST (°C) during the Last Glacial Maximum, ~18000 years ago.

Boundary conditions (shown above) used to produce general circulation models of past (e.g., COHMAP, 1988) and future climate change.

Comparison of observed continental- and global-scale changes in surface temperature with results simulated by climate models using either natural or both natural and anthropogenic forcings.

Relative changes in precipitation (in percent) for the period , relative to Values are multi-model averages based on the SRES A1B scenario for December to February (left) and June to August (right). White areas are where less than 66% of the models agree in the sign of the change and stippled areas are where more than 90% of the models agree in the sign of the change (IPCC, 2007).

Scenarios for GHG emissions from 2000 to 2100 in absence of additional climate policies (IPCC, 2007). SRES - (Special Report on Emission Scenarios, 2000).

CO 2 emissions and equilibrium temperature increases (above pre-industrial for a range of stabilization levels). Note the large discrepancy in outcomes. How do you account for this large discrepancy?

Atmosphere-Ocean General Circulation Model projections of surface warming ( and ). IPCC, 2007.

The 5th IPCC Assessment Report (AR5) was completed in You can access the report and data on line: