My Research

I am in the process of submitting a paper from part of my Master's work to a journal. I thought the introduction might give you an idea of what I study, if you're interested! I think the Amazon is a fascinating area to study! For fun, I'll also post some pictures from my trip to Manaus last November.

"The role of deep soil moisture in modulating climate in the Amazon rainforest"
Approximately half of the Amazon’s evergreen forests are subjected to dry seasons of at least three months [Nepstad et al., 1994], and yet the forest seems to thrive during the dry, sunny months. Understanding the mechanisms that enable the forest to live through extended dry periods is of particular importance considering that the effects of both global warming and land use change are predicted to cause a drier climate in this region [Oliveira et al., 2005].

The roots in the Amazon are well suited for dry season survival. Tap roots have been observed up to 11 m deep [Nepstad et al., 1994; Jipp et al., 1998]. Hydraulic redistribution (HR) allows the plants to access water from shallower soil layers, where most of a tree’s fine roots are located, and has been observed in three trees in the Tapajos National Forest in Brazil [Oliveira et al., 2005]. These adaptations increase a plant’s drought tolerance, enable the plants to maintain transpiration and carbon sequestration during seasonal droughts [Saleska et al. 2003; Oliveira et al., 2005], and have been shown to improve the seasonal cycles of evapotranspiration and carbon fluxes in land models [Lee et al., 2005; Baker et al., 2008, respectively]. However, few studies have looked at the effects of deep soils on climate in a coupled sense [e.g. Kleidon and Heimann, 1999; Lawrence and Chase, 2009]. This paper is a step in that direction.

By adding more realistic root and soil functions in the Simple Biosphere model, version three (SiB3), Baker et al. [2008] obtained more realistic results with regards to surface fluxes at certain sites in the Amazon. The goal of this paper is to examine the effects of these changes on the simulated hydrologic cycle when SiB3 is coupled to a single column version of a GCM. Ultimately, SiB3 will be coupled to a global GCM, and to a cloud resolving model which is then embedded as rows in GCM grid cells as a way of replacing typical cloud parameterizations. Therefore, this study lays the foundation for understanding the effects of certain soil biophysical properties on climate in the Amazon. The SCM is a useful tool for cutting the computational cost of coupled model development [Betts and Miller, 1986; Randall and Cripe, 1999] and facilitates testing parameters or diagnosing problems.

SiB, like other ecosystem models, previously had problems simulating fluxes of heat and moisture in the Amazon [Saleska et al., 2003; Randall et al., 1996; Liu, 2004]. In coupled runs of SiB2 and CSU’s GCM (BUGS5), Liu [2004] found that soil moisture stress led to decreased dry season transpiration and an overly dry and deep boundary layer, and ultimately to a complete shut-down of the hydrologic cycle in the Amazon. This result is analogous to the Amazon dieback found by Cox et al. [2004], where the forest transitioned to savannah due to decreased rainfall over western Amazonia in the 21st century [Cox et al., 2004]. Encouraged by the results of Baker et al. [2008], we investigate the climatic effects of including deep roots and more realistic ecosystem stress responses in SiB3. To study these effects, we coupled SiB3 to a single column version of BUGS5.

Unlocking the carbon cycle: the Eighth International Carbon Dioxide Conference

Here are some excerpts from an article I've written for the next issue of the AGU atmospheric science newsletter.

The most recent carbon cycle research was presented at the eighth edition of the International Carbon Dioxide Conference in Jena, Germany in September. Most of the talks were held in a plenary session, allowing the attendees to pick up as much information as possible. The communal atmosphere fostered discussion, feedback, and plans for future collaborations. What was learned from more than 500 posters and 100 talks could easily fill a comprehensive textbook on the carbon cycle. However, here we summarize some of the content of the meeting, which covered all aspects of the carbon cycle, including land and ocean sinks, atmospheric concentrations and transport, and fossil fuel emissions.

Oceans
Roughly half of the CO2 emitted by human activity each year remains in the atmosphere. The other half is split between the terrestrial biosphere and the oceans. Several talks focused on the oceanic sink for anthropogenic CO2. Andrew Watson, from the University of East Anglia, spoke about evidence for decadal changes in the oceanic carbon cycle, such as decreases in the anthropogenic CO2 at depth due to changes in deep water formation in the Labrador Sea from 1997 to 2003. These changes appear to be partially forced by anthropogenic climate change and partially by natural oscillations in oceanic circulation and the climate system. Such observations challenge the conventional assumption that the oceanic carbon cycle is in a steady state.

Land
Carbon scientists have been working to quantify the land carbon sink for more than a decade. Two talks focused on the roles of land use change and natural disturbances in the land sink. Richard Houghton, of the Woods Hole Research Center, estimated an annual flux of CO2 from land use change of 1.5 +/-0.7 petagrams of carbon (PgC). Conversion of forest to crops and pasture are the largest components of this flux. Depending on the dataset, tropical emissions from land use change in the 1990s was anywhere between 0.9 and 2.4 Pg C per year. Disturbances such as the pine beetle in the Canadian Rockies, fire and extreme drought result in disequilibrium in the strength of the land sink according to Yiqi Luo, from the University of Oklahoma. Quantifying these disturbances and understanding how climate change will affect them are essential tasks for quantifying the future land sink. Enhanced observational networks and experimental studies will be necessary for these to be achieved.

Anthropogenic CO2
Today we are at a point where science has proven that recent greenhouse gas increases in the atmosphere are due to humans. According to Pieter Tans, from at NOAA’s Climate Monitoring and Diagnostics Laboratory, we cannot afford to wait to take action. He cited a one-in-six chance that continental temperatures will rise by 20°F due to doubling CO2 [Roe and Baker, 2007]. “I think this is a chance we should not take,” he said. He claimed that the developing world carries the burden to reduce emissions, and “we need to demonstrate to developing countries that development is possible with very low emissions.” But what role will scientists play? Tans said that observations and atmospheric transport models can give assurance that emissions reductions are working. In doing this work, scientists must fully disclose their data and methods. He also recommended scientific assessment of proposed geoengineering solutions.

David Archer, from the University of Chicago, presented the long-term implications of not reducing fossil fuel emissions. Once emissions are cut, the amount of CO2 in the atmosphere will decrease over a period of several hundred years due to dissolution into the ocean. However, eventually the ocean’s ability to take up CO2 will be depleted, and CO2 will be removed from the atmosphere via reactions with calcium carbonate and silicate rocks. Once atmospheric CO2 and calcium carbonate reach equilibrium, approximately 10% of the carbon dioxide will remain in the atmosphere, Archer said. According to a study by Berner and Kothavala [2001], it could take 400,000 years before the last of the human-released CO2 is removed from the atmosphere. In other words, our actions today will impact climate on a geologic time scale. For example, Archer stated that emitting 5,000 gigatons of carbon would increase global mean temperature by 3°C for tens of thousands of years. Archer drove in his point of the long-term implications of fossil fuel emissions by saying, “It’s like somebody’s walking off a cliff. It will take them 10 seconds to hit the ground and you’re telling them the next 10 milliseconds won’t be all that painful.”

And some pictures of poster sessions and the dinner:

What determines the energy budget at the earth’s surface? (Day 1 of Global Climate Change course)

The energy budget at the Earth’s surface is an important thing to quantify because any imbalance will result in compensating changes in temperature. Primarily, the balance is between incoming solar radiation, outgoing terrestrial radiation, and radiation “trapped” in the atmosphere by the greenhouse gases (GHG’s: water vapor, carbon dioxide, methane, and nitrous oxide are the main ones).

On long timescales (hundreds of thousands to millions of years), climate is influenced by:
- distance from the sun and intensity of the sun,
- atmospheric composition (especially how many GHG’s there are),
- tectonics (locations of continents and oceans affect atmospheric and oceanic circulation patterns),
- Earth’s orbital path around the sun,
- volcanism (volcanoes emit GHG’s, although on the timescale of 1-2 years they have a cooling effect because the particles they emit also reflect solar radiation).

On short timescales, regional climate is determined by:
- the variation of solar radiation with latitude
- distribution of land and water (water retains heat through the winter because of its high heat capacity, while land has large temperature variations from winter to summer)
- ocean currents
- prevailing winds
- persistant high and low pressure areas (high pressure areas have sinking air that is warm and dry, low pressure areas have rising air and storminess)
- mountain barriers (rainy on the upwind side, dry on the downwind side)
- altitude

A lot of what we talked about was this general overview type information. It is what you would learn in a climate 101 course over the first few weeks, but we did almost all of it in one day – joy! More of this information can be found at: http://www.cmmap.org/learn/climate/causes1.html.

Activities today: A HW on what determines climate for different regions (similar to this map: http://www.cmmap.org/learn/climate/causes7.html. And a lab using a simplified model, which calculates the average surface temperature based on some of the 'long-term' climate forcings. It can be downloaded here: http://icp.giss.nasa.gov/education/geebitt (go for Mini-GEEBITT version B3).

Reading: We had them read Ch 2 from Ruddiman's textbook: Earth's Climate, Past and Future. I think this is a good textbook, but we chose to use papers for most of the class reading. Luckily, this chapter is available on the publisher's webpage (for now at least!). Also, there is a short paper by Jim Hansen from Science 2005 called: Earth's Energy Imbalance: Confirmation and Implications. It is a little meaty for the first day of a class, but I think it's a good overview of how the Earth's energy isn't balanced due to increasing GHG's in the atmosphere. So it helps set the stage for things we'll talk about later in the course.

Science and Climate Change Policy

here is a 2 piece article I wrote for the Atmospheric Sciences Newsletter for the American Geophysical Union. The first part covers the National Academy of Science and a bill being debated in Congress on climate legislation. The second is a more subjective overview of how useful/realistic the bill is.

What is the role of science in climate change policy?
Climate change policy is making headlines and generating heated debate recently, particularly regarding a cap and trade program in the U.S. On the forefront is the balance between mitigating and adapting to climate change, and protecting a faltering U.S. economy. The decisions that will ultimately be made require input from experts in many fields, and the National Academy of Science (NAS) has been asked for advice on climate change policy. While it is essential for policy-makers to be informed of the science behind the decisions they face, it is a precarious situation for scientists to be asked which course of action to follow.

In 2008, Congress asked the NAS (along with NOAA) to investigate and study climate change and to “make recommendations regarding what steps must be taken and what strategies must be adopted in response to global climate change, including science and technology challenges thereof.” Giving advice is why President Lincoln originally set up the Academy in 1863. The initial act creating the NAS charged it with investigating, examining, experimenting, and reporting on any scientific subject when called to do so by the government.

In response to Congress’ request, the NAS initiated a suite of studies called America’s Climate Choices (http://americasclimatechoices.org/index.shtml), which includes panels on limiting, adapting to, and researching climate change, and informing effective decisions and actions regarding climate change. The scientists involved plan to release a series of consensus reports later this year or early in 2010. The NAS also held a Summit on March 30 and 31 in Washington in order to discuss the U.S. response to climate change. Several hundred scientists, members of Congress, business leaders, and representatives of NGOs were in attendance.

Meanwhile, on March 31, Congressmen Henry Waxman (D-Calif.) and Edward Markey (D-Mass.) proposed a bill that addresses clean energy, energy efficiency, greenhouse gas emissions and the transition to a clean energy economy. The bill is called the American Clean Energy and Security (ACES) Act of 2009. The bill would require a transition to cap and trade and set target aggregate U.S. GHG emissions at 83% below 2005 levels by 2050, beginning with modest changes over the next few years (3% (20%) below 2005 levels in 2012 (2020)).

The difficulty for NAS is two-fold. There is a fine line between reporting on the science behind policy and giving prescriptive advice on which policy to pursue. The first problem is defining that line.

The second problem is the timeline. The House Energy and Commerce Committee began debate on the ACES Act on April 22 (Earth Day), but the reports from America’s Climate Choices aren’t scheduled to be released until the end of the year. On the other hand, House Speaker Nancy Pelosi said on April 21 that climate legislation will be passed this year, and then said on April 22 that it will be ready a year from now (Eilperin, 2009). Either way, a summary report from the NAS could prove beneficial for the House debates, perhaps overviewing the science and progress discussed at the Summit in March.

AGU’s position statement on Human Impacts on Climate states that, in regard to climate change, scientists should strive “to pursue research needed to understand it; to educate the public on the causes, risks, and hazards; and to communicate clearly and objectively with those who can implement policies to shape future climate.” In regard to Congress’ request from the NAS on advice on bills such as the proposed ACES Act, the Academy can take a similar approach – research the underlying climate change and technologies and clearly communicate their findings, all the while paying close attention to the line between objectivity and subjectivity. While this can be difficult, it is of extreme importance.

Sidebar: Putting the proposed ACES Act of 2009 into perspective
Are the emissions suggested aggressive enough to curb “dangerous” levels of climate change?
Juan Añel (now the Editor-in-Chief of this newsletter) wrote a relevant article to this question called “New energy and climate change strategy presented by the EU Commission” in Volume 1, Number 2 of the AS Newsletter. In it, he summarized the report from a EU Commission, which states “that global warming has to be limited to no more than 2°C above the pre-industrial temperature to prevent dangerous levels of climate change.”

The ACES Act would set U.S. targeted emissions at 20% below 2005 levels by 2020. According to the EU Commission, emissions from developed nations need to be reduced by an average of 30% below 1990 levels by 2020. However, as of 2006, the U.S. increased emissions by 14% since 1990. A 20% reduction from 2005 levels would be only roughly 8% below 1990 levels.

On the other hand, according to the EU Commission’s report, global emissions need to be 50% of 1990 levels by 2050. The proposed reduction of 83% of 2005 levels would be much greater than 50% from 1990 levels. This is an ambitious goal, but it would allow for developing nations to cut their emissions relatively less between now and 2050. However, it remains to be seen if modest decreases over the next decade will be enough to prevent 2°C warming over the next several decades. Although the proposed bill should be applauded (from an emissions-cutting standpoint) for its 2050 goal, the 2020 goal may be a case of too little too late.

Is it realistic to expect an 83% cut in emissions by 2050?
U.S. greenhouse gas emissions were the equivalent of approximately 6.1 GtCO2 in 2006. Meeting an 83% reduction would require the average American’s emissions to drop from 20 tons of CO2/year to 3.4 tons/year, assuming no population change. The good news is that the reduction could start small under the Waxman-Markey bill, which would also provide benefits such as “green” job generation and decreased American dependence on foreign oil. The EPA has estimated that the national economy would continue to grow under the bill between 2015 and 2030 (from $15 trillion to $22 trillion), although the average U.S. household would see an increased expense of $98 to $140 a year.

Rob Socolow and Stephen Pacala, co-directors of Princeton University’s Carbon Mitigation Initiative, proposed 15 strategies that are currently commercially available which could each prevent the emission of 25 GtC over the next 50 years [Pacala and Socolow, 2004]. According to their paper, stabilization of atmospheric CO2 is possible if global emissions stay below 8 GtC/year for the next 50 years. If work begins now, they argue, by 2055 we will have the technology to then begin decreasing global emissions. Naturally, emissions from developing countries will increase as population grows, which leaves it up to developed nations like the U.S. to strongly cut emissions, particularly over the next 50 years. Seeing how these technologies are available today, and that the U.S. is a wealthy nation despite recent economic woes, an 83% decrease by 2050 indeed seems feasible both financially and technologically.

Sources:
Añel, J. (2007), New energy and climate change strategy presented by the EU Commission, AGU Atmospheric Sciences Section Newsletter, 1(2), 3.
Eilperin, J. (Apr. 23, 2009), House panel begins debate on climate bill, Washington Post, http://www.washingtonpost.com/wp-dyn/content/article/2009/04/22/AR2009042202006.html
EPA: 2009 U.S. Greenhouse Gas Inventory Report: http://www.epa.gov/climatechange/emissions/usinventoryreport.html
Pacala, S. and R. Socolow (2004), Stabilization wedges: solving the climate problem for the next 50 years with current technologies, Science, 305, 968-972.
U.N. Framework Convention on Climate Change (UNFCCC): National greenhouse gas inventory data for the period 1990-2006.
http://unfccc.int/documentation/documents/advanced_search/items/3594.php?rec=j&priref=600004891#beg

Global Climate Change undergraduate course

Hello??!! Anyone out there? I haven't posted to this blog in months, but am planning on posting a recap of the undergraduate course I am wrapping up teaching. It is an entry-level class on global climate change, and is unique because it is about a quarter's worth of material covered in just 3-1/2 weeks! Insane!

This has been my first teaching experience and was/is overall positive. But it has been hard developing the course material as we go (I am co-teaching it with a geology professor). So I want to have a day-to-day record of what we did. Maybe I won't put it all on this blog (some of my presentations are huge), but I can put the outline of what was covered, selected readings, maybe assignments. If by some miracle a person who is planning a similar course comes across this, email me if you want more specifics and I'd love to share: abharper@atmos.colostate.edu.

At the bottom is the 16 topics we've covered. Over the next week or so, while this is still fresh in my mind, I'll be posting (ideally) once for each topic.
Here is some info about the course from the syllabus:
Goals and Scope of the Course
The goal of this course is to give you an understanding of how climate works and how climate is changing. You will learn about climate from a whole-earth point of view – taking into account interactions between the atmosphere, terrestrial biosphere, cryosphere, and oceans. We will, of course, study current climate change, but will also consider historical climate change and natural climate variability, and the impacts of these changes on societies and ecosystems. We will discuss climate models, climate predictions, and the concept of uncertainty as it pertains to the climate system.

Aside from these hard goals, we expect you to leave this class better prepared to interpret scientific data and results. This is a valuable tool whether you plan to become a scientist, teacher, politician … etc.

Schedule:
Each day’s lectures, labs, and discussions will be based upon a question that we wish to answer. By the end of the course, you should be able to answer or have a discussion about any of these questions. Also, the course will be broken up into 4 sections: the climate engine, causes of change, past change, and humans and climate.

What is the energy budget of the earth's surface?
How is heat transported around the world?
What is the importance of the carbon cycle?
What are feedbacks, and how do they work?
Why isn’t climate constant long term?
How has human society been impacted by climate change in the past?
Why is knowledge of past climate change useful?
What is a climate model and how is it useful?
Why isn’t climate constant short term?
How do humans act as agents of change?
How certain are we that current change is human-induced?
What is expected to change, and where?
What can we do about climate change and what are the responsibilities to the impacted?
What are some ways to engineer the climate and how are they physically possible?
What are some ways to engineer the climate and are they politically/ethically possible?
What are alternatives to carbon-based energy?