What are the key regional drivers of future climate change?

Globally, greenhouse gas forcing is the key driver in policy-relevent climate change (ie. over the next 20, 50, 100 years). Regionally -at the scales people live, ecosystems function, water is obtained and crops grown, other forcings can dominate. Land cover change, urbanization, industrial aerosols etc can all have regional fingerprints that while globally small are locally dominant. Other modes of variability, ocean-atmopshere coupling, land-atmopshere coupling, orographic effects etc all can be locally dominant drivers even if they are lost in any global measure of climate change. A research program to understand drivers of climate change at the scales that people live is hugely challenging at a scientific level, technical level for the modelling and in terms of research at the interface of risk and vulnerability.

How will marine communities respond to the interactive effects of ocean temperature change, increasing CO2 levels, decreasing pH, and other human-induced forcing over the next century?

Oceanic autotrophs account for about half of total global primary production. The food webs they support are important for a wide variety of human endeavors involving the sea, ranging from fisheries to coastal protection. Yet little is known about the synergistic effects of ongoing global changes on marine communities. Early evidence suggest that some organisms are highly sensitive to pH changes while others are available to take advantage of higher levels of dissolved carbon dioxide. How will species and communities respond to the sum of all forcing agents and at what timescales?

The principle obstacles to making progress in developing answers to this question revolve around the expense and difficulty of conducting ecological, physiological, and biogeochemical/climatic studies at sea.

How is the climate changing and why?

The global mean temperature in 2008 was the lowest since about 2000. Given that there is continual heating of the planet, referred to as radiative forcing, by accelerating increases of carbon dioxide and other greenhouses due to human activities, why isn’t the temperature continuing to go up? The stock answer is that natural variability plays a key role and there was a major La Niña event early in 2008, but this does not answer the question of where the energy has gone. Was it compensated for temporarily by changes in clouds or aerosols, or other changes in atmospheric circulation that allowed more radiation to escape to space? Was it because a lot of heat went into melting Arctic sea ice or parts of Greenland and Antarctica, and other glaciers? Was it because the heat was buried in the ocean and sequestered, perhaps well below the surface? Was it because the La Niña led to a change in tropical ocean currents and rearranged the configuration of ocean heat? Perhaps all of these things are going on? It turns out we can’t answer these definitively. Observations and attribution studies are inadequate. Has global warming really slowed or not?