Recent precipitation declines over the poleward and western margins of subtropical dry zones from North America to Australia are consistent with a reorganization of atmospheric dynamics attributable to global warming. But are these droughts attributable to anthropogenic forcings like increased GHG, aerosols and ozone, or are they within the realm of natural variability? The answer is not always clear. In the case of California…
The study of climate change, and realization that the Holocene, previously considered a period of great climatic stability experienced significant and dramatic disturbances, has occasioned new interdisciplinary study of the Maya, one of North and Central America’s great pre-Colombian civilizations. Scientists, anthropologists, archeologists, and historians have reinvigorated efforts to explain their sudden collapse, which took place from approximately 800-1000 CE in a period known as the Terminal Classic.
A changing climate effects the availability of water, agriculture, and virtually everyone on the planet. To predict changes in vegetation cover and adapt water usage appropriately it’s necessary to constrain changes in evaporative flux. Measuring evaporation is more challenging than other components of the hydrologic
The Intertropical Convergence Zone (ITCZ) — responsible for most of the precipitation on Earth — is defined by a pronounced maximum rainfall occurring 5◦ north of the equator over most ocean basins. The existence of an ITCZ directly derives from large…
Research published in Science highlights the potentially deleterious effects of climate change on global food security. As defined by the United Nations’ Food and Agriculture Organization, food security has a number of components. These include food availability, access and utilization…
Global warming simulations suggest that wet regions (where precipitation exceeds evaporation) will become wetter and dry regions drier by the end of the 21st century (e.g., Held and Soden 2006), with larger contrasts expected between dry and wet seasons (Chou et al., 2013). This ‘rich-get-richer’ behavior is consistent with a large increase in the moisture content of atmosphere, leading to enhanced horizontal moisture fluxes across regions.
Earth’s climate is characterized by persistent westerly jets (eastward flow) in the upper troposphere, located in the mid-latitudes of the Northern and Southern Hemisphere, which are associated locally with strong weather systems. The location of these jets is of paramount importance to human societies, as these are collocated with maximum in precipitation rates and surface winds in the extratropical regions.
A simple thermodynamic argument suggests that as the water vapor content of the atmosphere increases with global warming dry regions may become drier and wet regions wetter. This enhanced hydrological contrast with global warming can be attributed to changes in the atmospheric water vapor concentration being comparatively larger than those of the moisture advecting winds in the lower atmosphere.
Public discussions of climate change often focus on greenhouse gases and rising temperatures, but the most severe and immediate societal impacts of global warming are likely to be associated with changing hydrological conditions. Disruptions in water supply, extreme storms and record droughts may impact every aspect of rural and urban society: from agriculture and manufacturing to housing, energy and human health.