Water in the 21st century US

One major reason that it is difficult to achieve consensus about acting to reduce greenhouse gas emissions is the difficulty in grasping the magnitude of the climatic changes they will produce. The significance of a number like 3 degrees Celsius global warming over the next century is lost on most people: for one, many places experience that amount of temperature variation everyday, and much more than that every season. The fact that it is a global average also makes it a nebulous, if not irrelevant figure. Translating these abstract climate estimates to real world experience is a crucial step toward convincing decision-makers and the public about the need to tackle the problem.

Mike and I recently wrote a paper based on that premise: an attempt to help people in the U.S. visualize the local and regional scale environmental changes that are likely to happen over the coming decades. And rather than use temperature &/or precipitation, the two basic variables of climate, we used the availability of water as a means to synthesize their inter-linked significance. This linkage is seen, for instance, in the fact that if precipitation stays about the same over time, but it gets hotter, less water is found in streams or available for crops, because more evaporates. You can find the details and full article here, but the basic idea is to compare the patterns observed for the 20th century with those modeled for the end of the current century (around 2090) - thus changes that many of us are likely to at least begin to witness during our lifetimes.

When The Water Ends

One of the most difficult aspects of understanding just how a changing climate will manifest itself is that many of the environmental responses will be different from place to place. By all accounts, the most vulnerable locations are likely to be those regions already at the highest risk of experiencing water stress. Marginal lands where drought is common like Sub-Saharan Africa or the Great Plains.

The website Yale environment 360 recently posted an excellent (and short) 16 minute video describing the political and social fallout from changing patterns of precipitation and water availability near the border between Ethiopia and Kenya occurring over the last decade. It is a provocative look at how hunger, political instability, armed conflict, and patterns of humanitarian aid are all directly related to water. It underscores the real importance of climate to all of us. This issue is not just about the esoteric mechanics of atmospheric chemistry.

Climate change is also about shifting ecosystems, changing patterns of water availability, economic security, political stability, and social unrest. It is about what happens when the water ends. Take a look, I've linked to it below...

On Thinner Ice

Seasonal snowpack and glacial meltwaters from the Himalayan Plateau, often referred to as the water tower of Asia, supply fresh water to over 2 billion people in Asia. Snow and ice from the metaphorical roof of the world feeds every major river system in the region: the Indus, Brahmaputra, Ganges, Irrawaddy, Salween, Mekong, Yangtze and Huang He (Yellow). The Asia Society has released a short video (8 minutes long) entitled On Thinner Ice which uses repeat photography from the filmmaker David Breashears to document the retreat of some of the glaciers surrounding Mt. Everest.

It highlights the very real challenge of managing water resources in a changing world. At the same time population in these river basins is rapidly increasing and generating greater demand for fresh water, the glaciers supplying much of this water have been receding at unprecedented rates in recent decades. In a report published last year, the United Nations Environment Programme (UNEP) estimates that “67 per cent of the nearly 34,000 square km (12,124 square mi) of Himalayan glaciers are reported to be receding.”

This combination of increasing demand and decreasing supply is expected to lead to regional water shortages, compromised water quality and stream sedimentation throughout the region. While the mechanics of high-altitude/low latitude warming, glacial recession, seasonal snowmelt, and the timing of monsoonal rains can describe the variability of water supplies, the real impacts of these systemic changes cannot be calculated until the political, social, and economic pressures of a growing population with few resources to spare are accounted for.

This is vulnerability. As changing environmental conditions collide with social and economic pressures, some populations around the world will be more vulnerable and at risk than others.