The Effects of Climate Change
on Water Resources
Most people understand that greenhouse gases are affecting our world as the atmospheric protection is eroded by toxins being blasted into the air by large industry, and the emissions from cars and other vehicles. Satellite images show decreases in the protective ozone layer at the poles caused by human activity. Some greenhouse gases are needed to preserve the warmth of the planet: carbon dioxide, methane, water vapor and nitrous oxide all naturally exist in the atmosphere.
But the climate change that we see advancing unchecked comes from people habits and as large countries like China and India become more and more industrialized to serve the ballooning populations, even more toxins will be spewed into the atmosphere by more industry and more people driving cars. The smoke tunnels that we see in big industry contain huge amounts of halo-carbons released into the atmosphere. The problem is that halocarbons and carbon dioxide in large quantities interfere with the natural balance of the planet. The problem is compounded because the longevity for halocarbons and carbon dioxide is virtually unlimited and the increase is these cumulative emissions are hastening global warming.
The earth will restore itself by re-balancing climate system changes. Part of this process will mean the release of more heat covering the globe arising from accelerated evaporation of the oceans as they warm up, from precipitation and plant water vapor. All of this is part and parcel of the cyclical nature of hydrology.
- The warming of the planet increases changes in the circulation of ocean currents and the atmosphere above us. Global warming hastens the rate of water evaporation and it increases the capacity of the atmosphere to hold water. Water in the atmosphere is itself a greenhouse gas and the more water that evaporates due to climate warming, the more it insulates the warming effect already off balance due primarily to the burning of fossil fuels.
- The water vapor barrier released in to the atmosphere at an accelerating rate could nearly double the effects of carbon dioxide.
- Clouds increase warming by absorbing outgoing infrared radiation and help cool the earth by reflecting incoming solar radiation away from the earth. The total effects of changes in cloud cover will depend on a number of variables: how the warming will affect the creation of different cloud types and patterns, altitude and geographic location.
- Melting snow and glaciers create a darkening effect on the earth and this darkness inhibits the earth to reflect the harmful sunrays back into space. The atmosphere already laden with greenhouse gases is worsened by the captured carbon dioxide and methane. Future warming will escalate production of methane gas and decrease the ocean’s natural ability to remove carbon dioxide. As the world warms carbon dioxide is unable to be absorbed from the atmosphere since salt water can no longer absorb all of the carbon dioxide in the atmosphere. Added to this mix is the continuing spewing of other pollutants as a result of human activity. The small particles resulting from combustion such as sulphate aerosols, produce cooling by bouncing back sunlight into the atmosphere. Paradoxically the falling soot and dust that blanket snow resources actually increase warming because of the diminished capacity of the sun to reflect its rays back into the atmosphere.
Estimating the extent and consequences of future climate is an enormous challenge for researchers because of the numerous variables that impact change. When scientists conduct model simulations of future climate change, the results are often ambiguous, resulting in a wide range of temperature changes as greenhouse gases are increasing at different rates around the world. One of the greatest challenges of our future is to limit human activities that result in the in the emission of greenhouse gases.
The global warming we are already experiencing will increase exponentially unless we can slow greenhouse gas concentrations. As custodians of the earth, we must change the way we use energy technology, how we use the land and natural resources and manage population growth. The policies and practices we implement today will predict the future of the impact of global warming. There are two schools of thought on the amount of climate change that our future holds. An exploding population boom combined with insufficient technical progress and continued reliance on fossil fuels are estimated to result in dramatic climate changes by the end of this century.
Other experts predict slower population growth with technological advances that produce resource efficient technologies. Industry must adapt toward businesses that do not create an over abundance of toxins released into the air. The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report estimates that global average temperatures at the very least will increase by 1.1°C to 2.9°C by the end of the century. The Panel found that estimates projected for worse case scenarios fall in the range of between 2.4°C to 6.4°C.
So far international efforts to reduce the amount of greenhouse gas emissions have had little success as the damage has increased rapidly in recent years. Annual global emissions of the major greenhouse gases grew by 70 percent between 1970 and 2004, with an almost 10 percent jump between 2000 and 2004. The current amount of carbon dioxide in the atmosphere is calculated to be 381 parts per million compared with a concentration of carbon dioxide of 220 in pre-industrialized countries. The ratio has not been this high in at least 650,000 years.
We are on a collision course with the changing forces of nature. There is already demonstrative proof of climate change occurring around the world. The IPCC Fourth Assessment Report reported that the global average temperature increased by approximately 0.74 C in the century up to 2006. Eleven of the twelve hottest years since 1850 were between 1995 and 2006. The changes we are witnessing today are a portent of what is to come. The warming is creating havoc on natural processes, especially significant declines in summer sea ice across the Arctic, changes in migration patterns, melting glaciers and changes in precipitation.
Water resources will depend on rates of precipitation and evaporation and the amount of water contributing to runoff and groundwater recharge. The evaporation rate will be determined by a variation of factors, such as temperature, humidity, radiation and wind speed direction.
Climate model predictors indicate the most sensitive areas in the Arctic where ice loss is already having a detrimental effect on water levels. Global average precipitation will increase as temperatures rise. Scientists are predicting climate models are projecting a 5 percent increase in global average annual precipitation over land masses by the end of this century.
It is logical then to forecast that warming will increase the amount of rainfall and snowfall simply because the clouds will be laden with evaporated moisture. Even with global warming, seasons will still occur in some regions. Winter may mean snowfalls not seen since the age ice. In warmer weather, precipitation will be so heavy that our current infrastructures will not hold up. This was true with Hurricane Katrina that devastated the Gulf coast two years ago. Conversely, in other regions of the world, droughts will become more widespread as the warmer air temperature sucks evaporation from the soil. Global warming will not mean the same to everyone but its harsh affects will be felt around the globe.
There is still much unknown about short and long term changes such as water availability, water quality and flood risks. This is especially true on a regional basis. Global climate imbalance will cause changes, but not in a predictable way, at least not yet. So while average precipitation is expected to rise around the world, it does not necessarily translate to a worldwide deluge. Climate models reveal mixed patterns of precipitation change. Some areas will see drier weather than others and some regions will endure even more precipitation than they currently receive.
Current climate models are the best way we have right now to predict what will happen as the age of global warming rushes to reach humankind and all living things. The IPCC team analyzed a multitude of global climate models to determine commonalities in the direction and size of regional temperature and precipitation changes. The biggest finding was that almost all climate models showed that global warming will result in more precipitation at far north and far south regions of Canada, Antarctica and Russia. Global warming will create massive water release in high altitude regions of North America and Eurasia. Some models show the increase to be between ten and forty percent. The equator will be hard hit too as the surrounding areas are pummeled by rains heavier than we have seen before.
One thing the models consistently show is that many areas will become drier still. Based on the models it appears that a number of regions of the globe will become dry or drier: the Mediterranean basin, the U.S. Southwest and northern Mexico, southern Africa and parts of Australia (in southern hemisphere winter). Warming will increase how the atmosphere takes moisture out of the subtropics and sends it higher in the atmosphere. With the drying of subtropical land surface water will evaporate more quickly. Less precipitation will probably result because storm tracks will tend to move towards the poles while high-pressure systems centered over the dry subtropics will be larger. The projections for annual reduction in water runoff could be about 10% to 30% by the end of this century; that is, given a moderate rate of emissions. If emissions exceed those estimates in the future, parts of the world already struggling with not enough potable water will have a devastating effect on the people and the wildlife. Given that populations are rising, especially in countries such as India and China, the scenario plays out at its worst.
The scientific models currently being used to project wetter and drier regions of the world are less able to apply those models to smaller, regional areas. For the most part, changes in regional precipitation are harder to forecast than are changes in regional temperatures. In part, this is due to strong latitudinal differences in projected precipitation changes.
Estimations for more precipitation are greater in the northern hemisphere between the drying subtropics and far northern areas which includes the United States.
Global climate models are telling scientists that massive changes will affect the earth, in some places more extreme than others. The elements that are less predictable for a specific region are the location, amount and intensity of precipitation. But even when the models show small shifts in storm tracks, the amount of precipitation in a given area could be catastrophic.
Most climatologists use the Coupled Atmosphere-Ocean General Circulation Models (AOGCMs) to simulate how the atmosphere will change, given variables in higher levels of greenhouse gases and changes in other factors, both natural and human activity related. State of the art models measure the layers in the atmosphere and the oceans as well as sea ice. Simulations are run based on the interface of these variables to measure the effects of changes on land surfaces. The model for predictions of the atmosphere is rooted in the fundamentals of physics. Climate models construct a 3-D horizontal and vertical grid structure to check the movement of air pockets and the transfer of energy and moisture between pockets.
A major factor in the feasibility of climate modeling is the cost associated with producing models to perform the complexities required to simulate climates in the future. In order to shorten computing time and costs, most models use a coarse horizontal resolution. So the models replicate potential changes on a broad, but not detailed, basis. The models do not show details of the effects of mountain ranges and other unique topography of some surfaces on local climates. Scientists usually use a model with grid blocks running about 180 kilometers on a side. The coarse resolution does not reveal some landscapes as they really are – for instance, mountain ranges appear as a smooth set of ridges. Since large topographical features do have an effect on climate, forecasting regional changes is even more difficult and uncertain. As well, proximal mountain ranges tend to look contiguous as opposed to separate and distinguishable. For example the Great Basin in the western United States shows up as a water feature rather the desert that it is. The problem is the the Sierra Nevada Mountains skew the results because the coarse resolution shows the Basin on an upslope to the Rockies. Raw model output is not an effective tool to forecast changes in precipitation and runoff patterns, particularly when there are mountainous regions in the model view.
There have been several different models developed to improve resolution and present more accurate estimates of regional climate change. One method is to use a high resolution model adjusted for certain regional variables. Some statistical downscaling methods that adjust certain factors particular to the region can be used to enhance a realistic representation of current climate. Another promising model uses a high-resolution regional climate model to focus in on a particular area while the surrounding areas are shown in a coarser resolution so that the regional picture stands out. However, there are still limitations to calculating reliable local-scale projections. Models for the 21st century are under development but the complexities of the globe’s weather patterns make for slow progress.
