Gaseous Earth

Paleotempestology - Given the natural and anthropogenically-induced rise in sea surface temperatures (SST), it would be helpful to know if there is a relation between SST and hurricane frequency. As a result of recent developments in microsampling, it became possible for one of my students (Amy Lehigh University Dork Sahagian - Gaseous EarthFrappier) to use speleothems (stalagmites from caves) to measure the number of hurricanes in that past, and thus establish a quantitative relationship between climate and hurricanes. The results of application of this new environmental tool throughout hurricane-prone areas can be used to predict hurricane frequency and coastal impacts in populated or otherwise sensitive areas, and thus may be a useful tool for policy, insurance companies, and coastal management.
El Niño and the Carbon Cycle - While investigating speleothems for paleotempestology, we discovered an unexpected relation between El Niño and carbon isotopes. Each El Niño event was reflected in a large amplitude heavy carbon isotopic excursion. This was particularly puzzling because in Belize, where the initially analyzed speleothem is from, there has been no obvious climate signal from El Niño. This means that even in areas with little other response to ENSO, speleothems can be used as a proxy for El Niño events in the geologic past. Taking the next step, we have developed a few hypotheses regarding the mechanisms through which the El Niño signal is transmitted to speleothems. These have yet to be tested on the basis of analysis of vegetation, leaf litter, soil gas, soil moisture, ground water, and drip water. 
Climate Change Impacts on Ecosystems - Climate change is viewed by many as being the same as global warming. However we can hardly feel the difference of a  few degrees of atmospheric temperature. It Lehigh University Dork Sahagian - Climate change impacts on ecosystemschanges more than that every day and night, and much more winter and summer. However, the hydrologic cycle, and thus ecosystems, are extremely sensitive to minute changes in temperature, atmospheric circulation, and alterations in the exchange of water, carbon, and energy between the land surface and the atmosphere. The impacts on ecosystem goods and services vary from place to place, and matter at the regional scale, so global models need to be downscales to that level for projections of regional impacts. The US, for example, can be subdivided into several regions that feel these impacts differently. On the basis of model intercomparisons using various scenarios of future anthropogenic emissions and land use, regional projections can be made, and the difference between them indicate that global models are not, by themselves, sufficient for land use planning or resource management. It turns out that at the regional scale, dry places get drier, and wet places get wetter, but there are important differences in seasonality. As we improve our ability to resolve regional climate change impacts, it will be possible to more reliably reduce vulnerability to climate change impacts and maximize the provision of ecosystem goods and services.
Explaining Climate Change - While climate change is all around us, there are many who do not appreciate its importance  and even some who doubt its existence. Consequently, we must find more effective ways to communicate with policy-makers and the general public regarding climate change as a poster child of the disconnect between science and society.  There are 5 questions that need to be answered sequentially in discussion of climate change with a “climate contrarian.” These are relevant only to the extent that the individual in question accepts the fundamental tenets of science as a basis for decision-making. Some of our fellow citizens do not use direct observation, evidence, or science in general, as their primary basis for decision-making. No amount of factual education can alter this worldview, and it has become clear that other means must be found to prevent this segment of the population from making self-harming decisions, whether induced by disinformation or otherwise. We are far from saving this communication problem. However, regarding those for whom observation, analysis and conclusion (i.e. science) is a meaningful approach, these questions can be answered as follows:
1. Is climate changing?
Yes. There are undeniable instrumental data that temperatures are rising, precipitation patterns are changing, and ocean and atmospheric circulation systems are changing throughout the 20th and 21st centuries. Arctic ice and boreal snow cover is decreasing, storm tracks are changing, disease vectors are emerging, and precipitation patterns are changing.
2. Do people have anything to do with it?
Yes. Greenhouse gas emissions (primarily CO2 from fossil fuel burning) have to warm the atmosphere—it is what they do. The consensus of model results shows that the global climate is sufficiently sensitive to historic anthropogenic CO2 emissions to have already warmed by the amount measured over the last 150 years. In addition, CO2 triggers a water vapor feedback, greatly amplifying the effect, as warm air can hold more water vapor than cold air.
3. Is climate change bad?
Yes. While this is a more normative question to be considered by philosophers and the general public rather than by scientists, history has shown that any change in the environment of stable civilizations is disruptive to those civilizations. Alterations in areas in which crops can be grown, changes in phenology (when plants bloom or flower and leaves fall, and when insects emerge, etc.), shifting storm tracks, and rising sea level may have devastating economic, social, and political consequences to modern societies.
4. Can we do anything about it?
Yes. Because much of the warming caused by past emissions has already occurred, cessation of emissions can stabilize climate in the 21st century. Until they are overwhelmed, natural carbon sinks in the ocean and terrestrial ecosystems can continue to absorb previously emitted carbon and return global climate to the stable state in which civilization evolved over the last 10,000 years.
5. Is it worth doing anything about?
Yes.  Economic analyses indicate that the cost of adaptation to climate change in the form of agricultural disruptions, the value of and damage to coastal cities and infrastructure, and impacts of extreme events will be much greater than the cost of mitigation by transition to sustainable energy sources.
What we learn from the past is that nearly every major climate change in Earth’s history has been accompanied by changes in greenhouse gases, with warming associated with more CO2 and cooling associated with less. In the geologic past, before humans existed, climate and atmospheric CO2 concentrations varied together, with CO2 change not always predating climate change. This was due to the runaway feedbacks between temperature, CO2 in the atmosphere and ocean, and water vapor in the atmosphere. However, now that we have devised a way to inject CO2 directly into the atmosphere (fossil fuel burning), CO2 is preceding climate warming, which is already responding to the additional greenhouse gases.



Dork Sahagian  |  STEPS 424  |  1 West Packer Avenue  |  Bethlehem, PA 18015  |  phone 610-758-6379