Uncertainty in Climate Change

Climate change is typically defined as significant change in the measures that determine climate such as temperature, wind  or precipitation  over an extended period of time.  Factors that affect climate change include natural as well as human activity. One factor contributing to climate change is the increase of greenhouse gases in the atmosphere. While greenhouse gases help keep a moderating effect on the Earth’s temperature, the equilibrium of this system is changing with the rapid increase of greenhouse gases in the atmosphere caused by human activity. These human-driven activities include burning of fossil fuels, deforestation and urban and agricultural development. As the temperature in the atmosphere changes, climate changes occur. Climate change affects regions, ecosystems in those regions and even economies. According to the EPA Climate Change website, greenhouse gases are being monitored using a greenhouse gas inventory  which measures emitted or absorbed gases over a period of time. The EPA in the US tracks these absorptions and emissions as do many other countries, the data which helps formulate a global inventory. The use of these inventories help predict future emissions and absorptions. Trends, strategies and government policies are then formulated with the data collected.

There are several forcings and feedbacks that have raised questions and uncertainty about global warming. According to the  NASA GCC website, there are two forcings that scientists are looking at and developing future models for. One of the questions is about solar irradiance. There is no empirical data before the 1970’s so making conclusions based upon only forty years of evidence is difficult. Aerosols also raise some questions regarding their effects on  global warming. Aerosols are made of a variety of particles in both composition and size. Some of the lighter, brighter particles reradiate light back into the atmosphere while darker particles absorb the radiation thereby increasing temperature. Tracking of aerosols in the atmosphere has only been quantified in the last decade and the measurements make no distinction between the types of particles. According to the Earth Observatory website, some models have predicted that aerosol cooling can counteract global warming but the distribution of the particles is  not evenly distributed over the Earth.

Several feedbacks also raise some uncertainty because of insufficient data or knowledge. Cloud physics is not completely understood and difficult to model. Clouds cool the earth by providing shade and by reflecting light. They can suppress precipitation but could also form higher and taller clouds initiating more storms. According to the Earth Observatory website, clouds are a very large uncertainty in climate modeling and predictions. Carbon cycles involve both natural and human-made processes. Natural processes remove carbon emissions with oceans being the main repository. Ocean circulations especially in the Atlantic could potentially cool Europe and advance ice sheets. Data again is only represented since the 1990s.

Other models include those for precipitation. Some models predict a decrease in precipitation in the southwest US while other models ( JPL for example) show an increase in precipitation. NASA has also studied permafrost melt. As permafrost melts, it runs off into the oceans, increasing the amount of fresh water. Fresh water is less dense than salt water and floats on top. An increase of fresh water near the poles can change ocean currents which also affect atmospheric temperatures. Accuracy and uncertainty in climate models occurs due to insufficient or lack of long-term data as well as regional differences. Also contributing to the uncertainties is the incomplete climate knowledge as well as the natural variability of many factors contributing to climate change. . It is also difficult to predict exactly how much pollution humans will add to the atmosphere in years to come. (windows2universe.org). As we continue to explore and develop more climate models, these unknown factors will become more apparent. The data collected over a longer period of time will allow for more accurate predictions and mathematical relationships to be established. While time will indicate the extent of global climate change, it will also allow scientists to more accurately measure and use the data collected to predict more realistic scenarios.

Reviewing the 2007 IPCC report and the six emission scenarios proposed in the report, I can see many similarities regarding the evidence occurring today and possible future effects. With the burning of fossil fuels, our current global temperature is rising. With the  burning of fossil fuels without continued regulation (as seen in scenario A1F1), we will continue to see the global temperature rise. Human population is still increasing exponentially and more people on the planet will bring about more demand for resources. Some of the scenarios presented in the 2007 report reflect slow, isolated economies which can only hamper the progress that is being made in our time (A2). We are seeing some of the predictions for the next 100 years already occurring. We are seeing more flooding in low lying coastal and delta regions. Extinction rates are increasing due to climate change and the inability of some species to adapt to the changes. Migration patterns, flowering patterns and natural geologic events are changing due to changing weather patterns. We are seeing more severe weather events which in the report has predicted to only worsen. While many uncertainties are difficult to measure and collect data from, we can see effects already.  I think the biggest unknown factor in determining how the future scenarios will play out is human society itself. Will governments realize that policy changes and regulations need to establish to help combat the effects resulting by the  rise in global temperature  or will some governments resist change due to economic or political pressures? Will enough nations be able to sustain the demands on their economies that will occur with decreased crop production, increased disease and malnutrition? The IPCC have included some of these factors in their scenarios. While informing the public is crucial in addressing the problems we are facing now, it is paramount that we educate our young people. They are ultimately going to inherit the problems we are causing now and they will be the ones to hopefully find the solutions. The more  we address the unknowns and immeasurable factors in our lifetime, the uncertain factors that need to be investigated and studied, the easier the task will be for the future generations to implement more permanent solutions.