The topic of global warming is impossible to escape—it’s on television, in the papers, and all over the Internet. Scientists have compiled reams and reams of data about climate change, but plenty of non-scientists have added their voices to the discussion—and they have been drowning out much of the scientific information. But, if NASA has anything to say about it, the world will soon learn more scientific details about how our climate is changing.

Very soon, researchers will have the ability to collect precise data about our planet’s greenhouse gases and the action of photosynthesis on a global scale as it relates to our changing climate. On July 1, 2014, at 2:56 a.m., scientists from NASA’s Jet Propulsion Laboratory at the California Institute of Technology in Pasadena will launch a Delta II rocket from Vandenberg Air Force Base. This rocket will carry the Orbiting Carbon Observatory-2 (OCO-2)— the agency’s dedicated Earth-remote sensing satellite designed to study atmospheric carbon dioxide from space. The observatory will collect global measurements of atmospheric

CO2 with a high degree of precision so that scientists can identify sources and sinks of the gas by region. OCO-2 will also allow them to quantify CO2 variability over seasonal cycles over time.

OCO-2’s position will be within what is known as the A-train satellite constellation, a group of four French and American observation satellites in sun-synchronous orbits about 690 kilometers above the Earth. A-train is short for Afternoon Train, because the 98.14°- inclined orbit crosses the equator at around 1:30 p.m. solar time.

By meticulously charting the global carbon cycle, or the natural and human-caused events that influence the amount of CO2 in Earth’s atmosphere, OCO-2 will help humans to better understand and predict how changes in the abundance and distribution of greenhouse gases will affect Earth’s climate. And, it turns out, OCO-2 will also be able to track another valuable measure of climate variability: the changing

rates and affects of photosynthesis as they relate to carbon absorption activity, shown though spectroscopy as fluorescence. The realization that the observatory will be able to measure solar-induced chlorophyll fluorescence is a bonus: it was not originally planned to be part of the mission.

The OCO-2 Mission: A History of Innovation

Before OCO-2, there was OCO-1, a nearly identical spacecraft launched from Vandenberg Air Force Base in February of 2009. This observatory was lost to launch failure when the nose cone of the Taurus rocket carrying it failed to separate during ascent. After re-entering Earth’s atmosphere, it crashed into the Indian Ocean, near Antarctica. NASA’s Earth System Science Pathfinder Program sponsored this mission.

In between OCO -1 and OCO-2, Japanese researchers launched the Greenhouse gases Observing SATellite (GOSAT), an instrument that shares many design principles of the OCO spacecraft. It was intended to measure levels of carbon dioxide and methane, but NASA researchers, working in collaboration with their international colleagues, found an unexpected item amid the data: fluorescence from the chlorophyll in plants. The GOSAT was actually showing a faint green glow over Earth.

According to NASA’s Formulation Authorization Document, the scientists working on the OCO-2 Project will make every effort “to duplicate the original OCO design using identical hardware, drawings, documents, procedures, and software wherever possible and practical” to minimize risks to the project’s cost, schedule, and performance. Now that they are aware that the instrument will be able to record fluorescence as well, the mission has expanded.

One particular advantage of OCO-2 over GOSAT is its ability to record measurements at a rate of 24

per second. GOSAT makes a single observation every four seconds, meaning OCO-2 will be able to collect almost 100 times more observations of both CO2 and fluorescence.

About the OCO-2 Spacecraft

The OCO-2 instrumentation consists primarily of three high-resolution grating spectrometers (instruments that measure properties of light within the electromagnetic spectrum). The Orbital Sciences Corporation LeoStar-2 multi-mission spacecraft bus will serve as the on-orbit service platform for the instrumentation.

The spacecraft bus is made of aluminum honeycomb panels arranged in a hexagonal structure approximately one meter wide and two meters tall. Solar array wings, each approximately three meters long, are connected to each side of the spacecraft bus with movable motors. The mass of the entire observatory is approximately 450kg (or 990 lbs).

The United Launch Alliance Delta II 7320-10C launch vehicle will carry the OCO-2 observa-tory into orbit.

Our Planet’s Glowing Future:How NASA is Measuring Climate Change By: Kerry Connell

Fisher scientiFic

32 Prices are U.S. list prices — pricing may vary in CanadaComprehensive Sourcing for Laboratory Solutions

NO.1, 2014/ » ChemiCals » Chromatography » Consumables » lab equipment » life sCienCe no.2, 2014/

Why CO2 Matters

The plants and soils on land, the oceans, and other smaller regions steadily absorb carbon. These reservoirs of carbon are known as carbon sinks, and they reduce the amount of CO2 that remains in the atmosphere. The geographic distribution of carbon uptake is still uncertain. As more CO2 is emitted into the atmosphere, it will affect the efficiency of these sinks. To understand the global carbon cycle, we must understand where the carbon goes.

Since the Industrial Revolution, the concentration of heat-trapping CO2 in Earth’s atmosphere has increased from about 280 parts per million to more than 390 parts per million. In May of 2013, the Mauna Loa Observatory measured a record 400 parts per million of CO2. Ground-based measurement sites all over the globe have substantiated a 20% increase in atmospheric CO2 concentration over the past 50 years—the most significant change in CO2 observed in human history. According to the Global Carbon Project (an organization dedicated to studying the carbon cycle), the amount of CO2 added to the atmosphere through human activities has been steadily climbing.

OCO-2 will collect this information, along with other measures like fluorescence, and we will learn more about the spatial distribution of CO2 on Earth. Combined with ground-based measurements, the data will provide the information we need to better understand the processes that

regulate atmospheric CO2 and its role in the carbon cycle. This understanding is essential for improving predictions of future atmospheric CO2 increases and their effect on Earth’s climate.

Why Fluorescence Matters

With the advent of satellites that can measure greenhouse gases in Earth’s atmosphere, scientists can now also study solar-induced chlorophyll fluorescence. Solar-induced chlorophyll fluorescence is evidence of photosynthesis, the process by which plants convert sunlight into chemical energy. As chlorophyll molecules absorb radiation, some of the heat dissipates and some is re-emitted at a longer wavelength and seen as fluorescence.

By studying the faint glow of fluorescence from space, researchers will be able to better understand the productivity of plants by analyzing photosynthesis rates all over the world. “The rate of photosynthesis is critical because it’s the process that drives the absorption of carbon from the atmosphere and agricultural [food] production,” said Joseph Berry, a researcher in the Department of Global Ecology at the Carnegie Institution for Science in Stanford.

The measurement of fluorescence will help us understand how the plants on Earth are using CO2. The Global Carbon Project estimates that the burning of fossil fuels on Earth had produced nearly 35 billion tons of carbon dioxide by 2011— almost five tons of carbon dioxide for each of the seven billion people on the planet. Approximately half of the CO2 remains in the atmosphere; the other half dissolves in the seas or is taken up by organisms in the biosphere, creating carbon sinks.

“Data from OCO-2 will extend the GOSAT time series and allow us to observe large-scale changes to photosynthesis in a new way,” says David Schimel, lead scientist for the Carbon and Ecosystems research program at NASA’s Jet Propulsion Laboratory. “The fluorescence data may turn out to be a unique and very complementary data set of the OCO-2 mission.”

“OCO-2’s fluorescence data, when combined with the observatory’s atmospheric carbon dioxide measurements, will increase the value of the OCO-2 mission to NASA, the United States, and world,” says Ralph Basilio, OCO-2 project manager at JPL.

Photosynthesis: A Key to Carbon Use

Because plants need water to perform photosynthesis, this component of the carbon cycle determines the productivity of the plants. When the water supply is low, photosynthesis slows down proportionately. Scientists have been studying photosynthesis using chlorophyll fluorescence for decades, but only in the laboratory. Global-scale studies from space will fill in the blanks regarding how photosynthesis affects the Earth’s overall carbon budget.

Approximately 30 percent of all photosynthesis on land occurs in the Amazonian rainforest, which covers approximately 2.7 million square miles of South America. The location of more than half of Earth’s terrestrial biomass, this region is an enormous carbon sink. The only other area that comes close is the Arctic.

Older satellites were able to show scientists how green the Earth’s plants were—they were able to see how much leaf material was exposed to

sunlight. But because plants can still look green even when they are not photosynthesizing (and perhaps even dying), this is not a reliable measure of how productive the plants actually are. Solar-induced fluorescence, on the other hand, can show the precise amount of activity taking place.

The International Society for Optics and Photonics explains the molecular processes by which light is converted to energy: In a plant leaf, chlorophyll molecules are organized into macromolecular complexes called photosynthetic units, which contain chlorophyll molecules along with structures that process the solar photons the chlorophyll molecules absorb. Quantum coherence delocalizes the absorbed photon, or exciton, which is then subject to a variety of outcomes that occur at different rates. In one scenario, the enzyme photosystem II (PS2) uses the exciton to take an electron from water to make oxygen. In another, the exciton can exhibit radiation-free decay.

Continue >

0233U.S./CAN. P: 1.800.766.7000/1.800.234.7437 F: 1.800.926.1166/1.800.463.2996 www.fishersci.com/www.fishersci.ca

» ChemiCals » Chromatography » Consumables » lab equipment » life sCienCe

It could also be re-emitted as a fluorescent photon, or it could be shut down by regulated non-photochemical trapping centers (NPQs). When the potential flux of electrons exceeds the chemical capacity to use them for making sugars, NPQ activity increases, which results in changes in fluorescence yield while balancing supply with demand.

The ratio of this reaction rate constant to the sum of all the rate constants for the quenching of the excitons by these processes gives us the fluorescence yield. This means that solar-induced chlorophyll fluorescence represents molecular-scale events in the plants below —and these events are directly proportional to the product of absorbed photosynthetic radiation and fluorescence yield. When water is in short supply or temperatures are unfriendly to the plants in question, photosynthesis slows down —but light absorption continues. To achieve a balance, plants increase quenching by NPQs, which decreases fluorescence through reductions in fluorescence yield. Because plants often decrease their leaf

area when stressed, their ability to absorb solar

radiation is decreased, which reduces both photosynthesis and fluorescence.

Spectroscopic Measurement of CO2 and Fluorescence

As noted, the mission of OCO-2 is to survey the global geographic distribution of CO2 sources and sinks, but the observatory will not measure CO2 directly. Computer-based data assimilation models will use column-averaged dry air CO2 data to identity the location of these sources and sinks. In this process, OCO-2 will measure the intensity of the sunlight that CO2 reflects in a column of air, and diffraction grating will separate the incoming sunlight into a spectrum of multiple component colors for measurement by spectroscopy.

OCO-2’s polar, sun-synchronous orbit will allow global coverage with a 16-day repeat cycle. From its position in the A-train constellation, the observatory’s path will cross the equator at approximately 1:30 p.m. local

time. Acquisition at this time of day is ideal

for spectroscopic observa-tions of CO2 that use reflected

sunlight, because the high sun maximizes the measurement signal-to-noise ratio.

Carbon dioxide and oxygen molecules absorb light energy at highly specific colors (or wavelengths). Three parallel, high-resolution spectrometers, integrated into a common structure and fed by a common telescope, will simultaneously measure the carbon dioxide and molecular oxygen absorption of sunlight reflected off the same location on the surface of the Earth. OCO-2 will measure three small wavelength bands (Weak CO2, Strong CO2, and Oxygen O2) from the spectrum; absorption levels will indicate the presence of the different gases. By continually measuring the gases over the same location, OCO-2 will be able to track changes over time.

Aproximately 1% of the solar energy used by green plants is re-emitted as fluorescence, which appears to glow at wavelengths of around 690 to 800nm. Reflected solar radiation drowns out this much weaker fluorescent signal, so it has been impossible to quantify solar-induced fluorescence from space until now.

The new high-resolution spectrometers allow global fluorescence quantification by measuring the depth of Fraunhofer lines — narrow absorption indicators in the solar spectrum caused by

chemical elements in the sun’s photosphere. An emission source at the Earth’s surface (such as chlorophyll fluores-cence) reduces the fractional depth of these lines, meaning that the spectrometer can then pick them up. For instance, if a Fraunhofer line is opaque, showing 0% transmission, the radiance the satellite measures is the only light source in this narrow wavelength window —and therefore fluorescence. But because Fraunhofer lines are not entirely opaque, scientists use spectral fitting techniques to distinguish the amount of fluorescence from solar light reflected by the Earth’s surface and atmosphere.

Gross primary production, the gross uptake of atmospheric CO2 through photosynthesis, likely changes from season to season. Until now, scientists have had difficulty estimating this measurement, which is the largest variable factor in the global carbon budget. By quantifying global photosynthetic activity and efficiency, we can better understand where, when, and how the land and the atmosphere exchange CO2. This knowledge will help us to analyze the Earth’s carbon budget in a warming climate. OCO-2 will enable research-ers to derive solar-influenced fluorescence from space mea-surements and show that those measurements values correlate with gross primary production.

Data will begin to be available from OCO-2 about 45 days after

launch; scientists require some time to get the instrument positioned where it needs to be within the A-train constellation, and they must also test the components to ensure that everything is working as it should. Once OCO-2 is in work mode, it will store data on board and send it down to ground stations on Earth in bundles. The Jet Propulsion Lab will process the data, and the Goddard Earth Science Data & Information Services Center will distribute it to scientists and researchers everywhere.

Understanding — and Influencing — Our Planet’s Future

Since the early 20th century, the surface temperature of our planet’s air and oceans has increased about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980. Each of the three decades since has exhibited successively warmer temperatures at the Earth’s surface than any decade since 1850.

Instrumental measurement and charting are unequivocal, but scientists have also observed visual evidence of the warming of the planet. Sea levels have risen due to the melting of snow and ice; water above 3.98°C also expands as it warms up. The increased heat of the oceans, increased humidity, and earlier occurrence of spring events like the flowering of plants also show us that the climate is changing.

34 Prices are U.S. list prices — pricing may vary in CanadaComprehensive Sourcing for Laboratory Solutions

NO.1, 2014/ » ChemiCals » Chromatography » Consumables » lab equipment » life sCienCe no.2, 2014/

Writing in the July 2010 issue of the Bulletin of the American Meteorological Society, J. J. Kennedy states that the probability of these changes occurring by chance is virtually zero.

The Intergovernmental Panel on Climate Change (IPCC) reports that scientists are more than 90% certain that most of global warming is caused by increasing concentrations of greenhouse gases produced by human activities. In 2010, the national science academies of all major industrialized nations voiced their acceptance of that

assessment. In 2013, the IPCC stated that the largest driver of global warming is carbon dioxide emissions from fossil fuel combustion, cement production, and land changes like deforestation.

An increase in global temperature will bring about a rise in sea levels and a change in the amount and pattern of precipitation. Subtropical deserts will likely expand. Other potential effects include more frequent extreme weather events like heavy rains, droughts, and heatwaves along with ocean acidification and

species extinctions. Humans will experience a threat to food security from decreasing crop yields and loss of habitable land due to extreme flooding.

The overwhelming majority of scientists around the world agree that policy responses to climate change are necessary. Proposed changes include mitigation by the reduction of carbon emissions and the development of buildings resistant to the effects of extreme weather events.

In the future, using data like that collected by OCO-2, scientists may figure out ways to engineer the climate itself and allow humans to achieve some sort of control over the way the global carbon cycle works.

Policy may be political, but science is fact. Better data may bring about better understanding by demonstrating credible proof. If we’re lucky, this fact-based information will help the people of Earth to more fully understand science and the consequences of ignoring its factual data. The OCO-2 may

be the instrument that sets this understanding in motion so that we can more effectively adapt to our ever-changing world.

0235U.S./CAN. P: 1.800.766.7000/1.800.234.7437 F: 1.800.926.1166/1.800.463.2996 www.fishersci.com/www.fishersci.ca

» ChemiCals » Chromatography » Consumables » lab equipment » life sCienCe