Agata Buchwal-What Can Artic Shrub Tree Rings Tell Us?

Talk on 12/11/14

Agata Buchwal, a Fulbright Fellow from the University of Alaska in Anchorage wanted to know what can we learn from tree rings in Artic shrubs’ annual growth? She realized that the Artic is like a desert in that it has very little life and knowing what goes on there is crucial especially because the Artic has a great deal of control over the temperature due to it being one of the greatest sources of cold climate. The Artic is also a hotspot for global change and has evidence of site and species specific response to change. Both of these important phenomenon led her into researching her topic on annual growth patterns in Artic shrubs.

The Artic has “high resolution data and might be a proxy for validation and reconstruction on records”.  She noticed that from global warming, there has been an overall greening and warming effect which is affecting the flora, but how? In most cases, plants are active in growth only during the summer months due to more sunlight (for photosynthesis) and warmer temperature. She found that these dwarf shrubs are actually becoming more active in summer and winter months. She saw evidence of this in patterns in tree ring growth. Buchwal analyzed the tree rings of 10 shrubs, but noticed that she was getting little records from the rings and in fact, there were huge gaps in years with no growth. She decided to take a different approach to analyzing tree rings and instead dug deeper into the ground to analyze the rings under the surface, which is not standard procedure. When she analyzed those below surface rings, she found a more concrete story leading her to believe that dendrochronologist may be missing out on key information by not measuring and comparing above and below surface rings. Another main point she stressed in the talk was that the Artic needs to be explored further to get a better indication of climate change and how species and sites can adapt to change.

Agata still has many unanswered questions brought up while analyzing her results. How many observed shrubs actually have missing rings and how many are actually wedging rings? Due to current measurement methods, some rings may be misanalysed and counted as missing when they are really a wedge ring (partially missing ring). Are we measuring tree rings wrong and leaving out key data by not measuring rings from below the surface (roots)?

Up next on Agata’s academic journey is to look at our local Tundra in Alaska to see if there are similar tree rings results as found in Tundra of the Artic. She also wants to run experiments to see how plants will deal with a 2 degree Celsius increase in temperature (result of Global Warming). She suggests bringing many different diverse experts to help bring in different ideas to piece the story together. Buchwal also wants to know (in future research) how water is being dealt with based on the evidence from the tree rings, for example, can we see if the plants are using precipitation or melting permafrost more efficiently based on the ring evidence.

Atmospheric sciences dept talk on Saharan drought

FROM STEPHAN HLOHOWSKYJ

Atmospheric sciences dept talk on Saharan drought            

As humans improve their understanding of climate it is becoming more apparent that to fully characterize the Earth we need not only to improve climate models, but also expand and develop observational data. In North American we take for granted the availability of observational networks and records that roughly span the past 100 years (or more in some cases!). Stable governments and economic situations have allowed many different agencies, scientists, and citizens to contribute to climate data. However, in other regions of the world such data do not exist. The difficulty of acquiring climate data can stem from various obstacles such as, dangerous political situations, high cost, war, and famine. This has been the case for many countries, in the Sahara Desert region of Africa. For example the current and ongoing civil war in Mali has prevented western scientists from visiting the region to work with local climatologists. Despite this, there are still many researchers that are making progress to understand, characterize and document climate in Northern Africa.

            Dr. Amato T Evan (Assistant Professor of Climate, Atmospheric Science & Physical Oceanography at Scripps) is part of a research team that has worked on climate in the Sahara Desert. His research has found that the dynamics controlling Sahara Desert temperatures can cause changes in the position of the Sahel (West African) Monsoon, as well as, play a role in Atlantic Ocean surface temperatures. This enormous region (over 9.4 million square kilometers) is still being characterized due to limited observational data sets. A collaborative effort between the Algerian government, French government and Scripps institute have been working to produce a meteorological data beginning in the 1970's in the Western region of the Sahara. Dr. Evan was recently hosted by the department of Atmospheric Sciences at the University of Arizona, to present his findings from analyzing this collaborative data set. At his seminar, Dr. Evan gave new insights into atmospheric processes controlling not only temperatures over the Sahara Desert but also the position of the Sahel Monsoon. His findings suggest that as temperatures increase over the Sahara, moist air is brought in due to convection and the increased water vapor pressure in the atmosphere feeds back on temperature. Much like the urban heat island effect, the increase of water vapor causes temperatures to stay warmer particularly at night. During the day long wave radiation is adsorbed and remitted to the surface of the desert, while short wave radiation is scattered offsetting the heating of the surface. However at night since there is no more shortwave radiation (after sunset) the long wave radiation absorbed by water vapor during the day is remitted. Since the Sahara is already a very dry region, the results suggest that only small changes in water vapor pressure were needed to make a big difference in surface heating. Dr. Evan termed this process as SWAT (Sahara WAter Moisture and Temperature) feedback, since as nighttime temperatures increase, so does daytime convection and therefore more moist air is drawn in from surrounding regions (e.g. Atlantic and Mediterranean). This can effect the position of the Sahel Monsoon, and also likely influence droughts in the region. Since we already know that ocean temperatures are increasing, Dr. Evan predicts that the SWAT feedback coupled with changes in the Atlantic Ocean may cause the monsoon to not travel as far north rather staying around the Gulf of Guinea. This raises the concern that long term “Megadroughts” could become a more common as the SWAT feedback intensifies in concert with anthropogenic climate change over the next 100 years. These findings reiterate the need for increased observational data not only in Northern Africa but all over the world in order to better understand climate change.

http://www.globalpost.com/dispatch/news/regions/europe/141211/europe-energy-supergrid-climate-change-carbon-emissions

http://www.globalpost.com/dispatch/news/regions/europe/141211/europe-energy-supergrid-climate-change-carbon-emissions

Blog on Science Cafe, September 16, 2014 at Magpie Pizza

Rodrigo Valdés

Over last decades global change has been one of the most important fields of study for researchers of different disciplines. This is because its development and impacts include different natural and anthropogenic processes that are very difficult to analyze e.g. potential effect on people, potential to slow or stop it, influence on so many aspects of society, etc. Despite now there is a better understanding about the possible functioning of global climate change, still there are a lot of questions that must be answered in order to generate appropriate adaptation and mitigation activities. For instance, how will global warming impact future climate scenarios?. Or what does climate change mean for the future of our planet?. The Regents Professor Jonathan Overpeck from Geosciences and Atmospheric Sciences departments at the University of Arizona has been working on understanding the impacts of global warming in climate extremes over the southwestern United States (SWUS), but also in a global scale. He has published more than 170 papers in climate and the environmental sciences and served as a coordinating lead author for the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment (2007). On Sept 16^th 2014, Professor Overpeck presented a talk titled “Global Warming: Implications for Changing Climate Extremes”, where it was possible to observe recent results about the impact of global warming on climate extremes. The talk was divided among four different types of impacts: 1) Temperatures, 2) Precipitation, 3) Droughts, and 4) Hurricanes (Cyclones).

Climate Event 1: “More frequent and longer warm spells and heat waves”. This pattern has been observed in many regions of the world, i.e. Australia, Europe, and SWUS. Global maps of increased number of warm days/nights and decreased number of cold days/nights showed that almost all the world is getting warmer. These increased changes in temperature patterns have likely been forced by human activity and it is highly probable that in the future will be a sure impact for the SWUS.

Climate Event 2: “More frequency, intensity, and amount of heavy precipitation”. Because increased rates of evaporation, the atmosphere has now more moisture that affects precipitation patterns, which is also influencing the intensity and magnitude of floods. For example, heavy storms pounded Arizona on Sept 8^th 2014, where daily rainfall of 1.26 in. was recorded at the Tucson Airport. The National Weather Service stated that this recent event broke the old record of 0.94 in. observed in 1919.

Climate Event 3: “Increase in intensity and duration of droughts”. Droughts are a combination of precipitation and temperature interactions. NOAA indicated that between 2010 and present droughts have generated economic impacts of more than US $40 billion and the loss of 218 human lives in the United States alone. Additionally the longest drought in SWUS since raingauges records exist continues (15-year drought), and the impacts of this phenomenon can be clearly observed in Lake Powell. Mega-droughts have more intensity and duration, and they are powerful, dangerous and hard to detect. They have occurred in the past, and they are still out there, i.e. the chances of having a three-decade-long drought is about 20%-50-% for SWUS in the coming century.

Climate Event 4: “Increase in intense tropical cyclone (hurricane) activity”. This phenomenon occurs mainly in the in the Atlantic Ocean, and their statistical changes are very hard to detect in the data from elsewhere because observations are still too short. This also has a certain degree of relation to precipitation intensity, because storms should lead to more intense rain.

According to Overpeck’s conclusions most of the changes stated above are currently happening around the entire globe; however, each one of these changes has regional components. Some of them have been influenced by human activity, and it is likely that in the future they will be almost a sure bet, which means that anthropogenic warming will probably make all of these changes worse. However, there is still uncertainty about what is the bottom line for these changes, how strong they will be impacting our planet, what the human action can make to minimize climate change?, and where will this lead next? .

To save the planet (cont'd)

It turns out that Nadine Unger's Op-Ed in the NY Times ("To save the planet, don't plant trees"), cited in my previous post, has attracted quite a bit of attention. See in particular the open letter by a group of scientists strongly disagreeing with the Op-Ed.

And for an excellent, readable critique whose elements should sound familiar to those who followed my lecture on Land Use, see the piece by my colleague, Abby Swann, from the University of Washington, posted at the RealClimate blog.

Seems like this should make good material for our upcoming mid-term!

To save the planet, don’t lose the forest for the trees?

Atmospheric chemist Nadine Unger, writing in the September 19, 2014 New York Times Op-Ed page advises us:  "To save the planet, don't plant trees."  She wirtes there that “the science says that ... climate change mitigation [through] forestry is high risk” and “a bad bet.”  

With today's lecture on land-use change as a driver of climate change, this issue is well-timed for our class to consider.  What do you think?   Let us know in the comments section below, or as your own post to the blog.

Any comment or post will bring extra credit in the from of an extra point on the just completed mid-term (the best posted comment will gain 2 points!).