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Providing Insight
Into Climate Change
Climate Change Science Essay page 9

CO2 Increases Plant and Forest Growth

CO2 is a major plant fertilizer. The increase in CO2 emissions have caused increased crop yields and faster growing plants and forests, thereby greening the planet.Estimates vary, but somewhere around 15% seems to be the common number cited for the increase in global food crop yields due to aerial fertilization with increased carbon dioxide since 1950. This increase has both helped avoid a Malthusian disaster and preserved or returned enormous tracts of marginal land as wildlife habitat that would otherwise have had to be put under the plow in an attempt to feed the growing global population. Commercial growers deliberately generate CO2 and increase its levels in agricultural greenhouses to between 700 ppm and 1,000 ppm to increase productivity and improve the water efficiency of food crops far beyond those in the somewhat CO2 starved atmosphere. CO2 feeds the forests, grows more usable lumber in timber lots meaning there is less pressure to cut old growth or push into "natural" wildlife habitat, makes plants more water efficient helping to beat back the encroaching deserts in Africa and Asia and generally increases bio-productivity.  See here

A major study (Zhu 2016) by 32 authors from in eight countries found a widespread increase of greening over 25% to 50% of the global vegetated area, with the CO2 fertilization effect explaining 70% of the observed greening trend. Green leaves produce sugars that are the source of food, fiber and fuel for life on Earth. The warming climate since 1982 explains 8% of the greening trend, predominantly in the high latitudes and the Tibetan Plateau. The study used three satellite leaf area index records to determine the greening trends and used ecosystem models to allocate the greening trends during 1982 - 2009 among four key drivers. The increase in vegetation is considerably larger than suggested by previous studies. Lead author Dr. Zaichun Zhu said “The greening over the past 33 years is equivalent to adding a green continent about two‑times the size of mainland USA (18 million km2)”. The abstract is here. See comments by Nic Lewis.  The map below shows the percentage change in leaf area from 1982 to 2015.

Leaf area change

A paper by Donohue et al published May 2013 here finds that "satellite observations, analyzed to remove the effect of variations in precipitation, show that cover across [warm and arid] environments has increased by 11%. Our results confirm that the anticipated CO2 fertilization effect is occurring alongside ongoing anthropogenic perturbations to the carbon cycle and that the fertilization effect is now a significant land surface process." The paper's conclusions states, "Both satellite and ground observations from the world’s rangelands reveal widespread changes toward more densely vegetated and woodier landscapes. Our results suggest that increasing CO2 concentrations in the atmosphere has played an important role in this greening trend and that, where water is the dominant limit to growth, cover has increased in direct proportion to the CO2-driven rise in water use efficiency of photosynthesis."

Donohue GRL May2013 Map greening of the earth

Estimated changes in vegetative cover due to CO2 fertilization between 1982 and 2010 (Donohue et al., 2013 GRL).

Bigtooth Aspen Growth Response to Enhanced CO2 and Temperature

Bigtooth Aspen Growth Response to Enhanced CO2 and Temperature


Jurik et al. (1984) exposed bigtooth aspen leaves to atmospheric CO2 concentrations of 325 ppm and 1935 ppm and measured their photosynthetic rates at a number of different temperatures. At 25C, where the net photosynthetic rate of the leaves exposed to 325 ppm CO2 is maximal, the extra CO2 of this study boosted the net photosynthetic rate of the foliage by nearly 100%; and at 36C, where the net photosynthetic rate of the leaves exposed to 1935 ppm CO2 is maximal, the extra CO2 boosted the net photosynthetic rate of the foliage by a whopping 450%. These results are similar to studies of many other plants.

             Young Eldarica Pine Tree Growth Response to CO2

Young Eldarica Pine Tree Growth Response to CO2


Young Eldarica pine trees were grown for 23 months under four CO2 concentrations and then cut down and weighed. Each point represents an individual tree. Weights of tree parts are as indicated. See here.

                                    Wheat Yield Response to CO2

Wheat Yield Response to CO2


This graph shows the response of wheat grown under wet conditions and when the wheat was stressed by lack of water. These were open-field experiments. Wheat was grown in the usual way, but the atmospheric CO2 concentrations of circular sections of the fields were increased by means of arrays of computer-controlled equipment that released CO2 into the air to hold the levels as specified. Average CO2-induced increases for the two years were 10% for wet and 23% for dry conditions.

Since atmospheric CO2 is the basic "food" of nearly all plants, the more of it there is in the air, the better they function and the more productive they become. For a 300 ppm increase in the atmosphere's CO2 concentration above the planet's current base level of slightly less than 400 ppm, for example, the productivity of earth's herbaceous plants rises by something on the order of 30% (Kimball, 1983; Idso and Idso, 1994), while the productivity of its woody plants rises by something on the order of 50% (Saxe et al., 1998; Idso and Kimball, 2001). Thus, as the air's CO2 content continues to rise, so too will the productive capacity or land-use efficiency of the planet continue to rise, as the aerial fertilization effect of the upward trending atmospheric CO2 concentration boosts the growth rates of nearly all plants. A 2003 study using 18 years (1982 to 1999) of satellite observations shows that global net primary plant production increased 6% over 18 years. The largest increase was in tropical ecosystems. Amazon rain forests accounted for 42% of the global increase in net primary production. See here.


Elevated levels of atmospheric CO2 have been conclusively shown to stimulate plant productivity and growth. A study by Idos published by CO2Science shows the monetary benefit of the atmospheric CO2 fertilization effect of forty-five crops that supplied 95% of the total world food production over the period 1961-2011.The annual total monetary value of this benefit grew from $22.7 billion in 1961 to over $170 billion by 2011, amounting to a total sum of $3.9 trillion over the 50-year period 1961-2011, all in US2016 dollars. See the study by CO2Science here.

The world's population is 7.7 billion and increasing at 1.18% per year. People will require increasing quantities of food and more natural ecosystems will be lost to crops and pastures. The resulting loss of habitat may result in species extinctions if crop yields are not significantly increased. Unfortunately, the rate of increase of crop yields is declining as crops are approaching the genetic yield limits. Increasing crop yields on existing farmlands would help to save lands for nature. If crop yields fail to increase, humans will suffer more frequent famines. Fortunately, the increase in CO2 concentrations will substantially enhance crop yields and is essential to prevent or delay the destruction of habitat and animal species, and may allow us to produce sufficient agricultural commodities to feed the growing population. Any action taken by us to slow or reverse the increase in CO2 concentration in the air may result in more frequent famines and species extinctions.

See here from CO2Science.

Kyoto Protocol - Misallocation of Funds

Of all the major problems of the world, climate change is one of the least important because funds spent to reduce CO2 emissions will have an insignificant effect on climate. Computer model projections show that full implementation of the Kyoto Protocol may result in temperature reduction of an undetectable 0.06 Celsius by 2050 at a cost of about $1,000,000,000,000 US. See here. (This estimate assumes the sun has no effect on climate. Since the sun has a major effect, the 0.06 Celsius estimate is likely high by a factor of 2 or more.)

The Copenhagen Consensus (directed by environmentalist Bjorn Lomborg) analysed the major challenges facing the world and produced a prioritized list of opportunities responding to those challenges. Submission by 24 United Nations ambassadors and other senior diplomats were reviewed by economists and determined that the top priority for addressing major world challenges would be given to communicable diseases, sanitation and water, malnutrition, and education. Ranked toward the bottom of the 40-category list were issues relating to climate change and the Kyoto Protocol.


Warming on Other Planets

If the Sun is the primary driver of climate change, one should expect to see evidence of recent warming on other planets. As the Earth has warmed over the last 100 years, so too has Jupiter, Neptune, Mars and Pluto.

Jupiter is the largest planet in the solar system. Its most distinctive feature is the great Red Spot, which is a huge storm that has been raging for over 300 years. A new storm, called Red Spot Jr. has recently formed from the merger of three oval-shaped storms between 1998 and 2000. The latest images from the Hubble Space Telescope suggests that Jupiter is in the midst of a global change that can modify temperatures by as much as 10 degrees Fahrenheit on different parts of the globe. The new storm has been rising in altitude above the surrounding clouds, which signals a temperature increase. See here from

Jupiter Red Spot

Neptune is the furthest planet from the Sun (Pluto is now a dwarf planet) and orbits the Sun at 30 times the distance from the Sun to the Earth.
                                                   Neptune Warming

Neptune Warming


In the recent article, Hammel and Lockwood, from the Space Science Institute in Colorado and the Lowell Observatory, show Neptune has been getting brighter since around 1980; furthermore, infrared measurements of the planet since 1980 show that the planet has been warming steadily from 1980 to 2004.

In the figure, (a) represents the corrected visible light from Neptune from 1950 to 2006; (b) shows the temperature anomalies of the Earth; (c) shows the total solar irradiance as a percent variation by year; (d) shows the ultraviolet emission from the Sun. All data has been corrected for the effects of Neptune's seasons, variations in its orbit, the apparent tilt of the axis as viewed from the Earth, the varying distance from Neptune to Earth, and changes in the atmosphere near the Lowell Observatory.

See here for more information.

There is also strong evidence of global warming on Neptune's largest moon, Triton, which has heated up significantly since the Voyager spacecraft visited it in 1988. The warming trend is causing Triton's frozen surface of Nitrogen gas to turn into gas, making its atmosphere denser. See here.

A recent study shows that Mars is warming four times faster than the Earth. Mars is warming due to increased Sun activity, which increases dust storms. The study's authors led by Lori Fenton, a planetary scientist at NASA, says the dust makes the atmosphere absorb more heat causing a positive feedback. Surface air temperatures on Mars increased by 0.65 C (1.17 F) from the 1970s to the 1990s. Residual ice on the Martian south pole, they note, has steadily retreated over the last four years.  Thermal spectrometer images of Mars taken by NASA's Viking mission in the late 1970s were compared with similar images gathered more than 20 years later by the Global Surveyor.

Mars polar ice cap

Mars polar ice cap

See here and here for more information.

The demoted planet Pluto is also undergoing warming according to astronomers. Pluto's atmosphere pressure has tripled over the last 14 years, indicating rising temperatures even as the planet moves further from the Sun. See here for further information.


An Inconvenient Truth

Al Gore's movie "An Inconvenient Truth" (AIT) is grossly misleading about climate change. Nearly every major statement made in the movie is one-sided, exaggerated, or plainly false. This movie has had a large effect on public opinion even though most scientists agree it is misleading.

Some of the problems with AIT are:

Implies that, during the past 650,000 years, changes in carbon dioxide levels largely caused changes in global temperature, whereas the causality mostly runs the other way, with CO2 changes trailing global temperature changes by hundreds to thousands of years. Never mentions that global temperatures were warmer than the present during each of the past four interglacial periods, even though CO2 levels were lower.

Presents images showing what 20 feet of sea level rise would do to the worlds major coastal communities. There is no credible evidence of an impending collapse of the great ice sheets. We do have fairly good data on ice mass balance changes and their effects on sea level. NASA scientist Jay Zwally and colleagues found a combined Greenland/Antarctica ice loss sea level rise equivalent of 0.05 mm per year during 1992-2002. At that rate, it would take a full century to raise sea level by just 5 mm.

Presents the hockey stick reconstruction of Northern Hemisphere temperature history used by the IPCC, according to which the 1990s were likely the warmest decade of the past millennium. It is now widely acknowledged that the hockey stick was built on a flawed methodology and inappropriate data.

Assumes a linear relationship between CO2 levels and global temperatures, whereas the actual CO2-warming effect is logarithmic, meaning that each 100 ppm increase in CO2 levels adds less warming than the previous 100 ppm increase. A 100 ppm increase to 600 ppm increases temperatures by 63% of a 100 ppm increase to 400 ppm.

Claims that the rate of global warming is accelerating, whereas the rate has been constant for the past 30 years to 2002 roughly 0.17°C per decade, and no warming from 2002 through 2014.

Claims that Lake Chad in Northern Africa is drying up due to global warming. The lake is the water source for 20 million people, and it has an average depth of only 1.5 to 4.5 meters. It has actually been dry multiple times in the past: in 8500 BC, 5500 BC, 2000 BC and 100 BC. The lake has shrunk in size due to a rapidly expanding population drawing water from the lake, the introduction of irrigation technologies and local overgrazing. These causes are neither global nor warming, and are utterly independent of CO2. In addition, Africa as a continent experienced a dramatic shift towards dryer weather in the end of the 19th century that is not generally attributed to CO2.

Distracts views from the main hurricane problem facing the United States: the ever-growing concentration of population and wealth in vulnerable coastal regions, which is partly a consequence of federal flood insurance and other political subsidies.

Blames global warming for the decline since the 1960s of the emperor penguin population in Antarctica, implying that the penguins are in peril, their numbers dwindling as the world warms. In fact, the population declined in the 1970s and has been stable since the late 1980s.

Never explains why anyone should be alarmed about the current Arctic warming, considering that our stone-age ancestors survivedand likely benefited fromthe much stronger and longer Arctic warming known as the Holocene Climate Optimum.

Presents one climate models projection of increased U.S. drought as authoritative even though another leading model forecasts increased wetness. Climate model hydrology forecasts on regional scales are notoriously unreliable. Most of the United States, outside the Southwest, became wetter during 1925-2003.

Blames global warming for the record number of typhoons hitting Japan in 2004. Local meteorological conditions, not average global temperatures, determine the trajectory of particular storms, and data going back to 1950 show no correlation between North Pacific storm activity and global temperatures.

Claims that global warming endangers polar bears even though polar bear populations are increasing in Arctic areas where it is warming and declining in Arctic areas where it is cooling. In fact 11 of the 13 main groups in Canada are thriving, and there is evidence that the only groups that are not thriving are in a region of the Arctic that has cooled. Polar bears have survived the Holocene Climate Optimum and the Medieval Warm Period, both periods were significantly warmer than today's climate.

Warns that a doubling of pre-industrial CO2 levels to 560 ppm will so acidify sea water that all optimal areas for coral reef construction will disappear by 2050. This is not plausible. Coral calcification rates have increased as ocean temperatures and CO2 levels have risen, and todays main reef builders evolved and thrived during the Mesozoic Period, when atmospheric CO2 levels hovered above 1,000 ppm for 150 million years and exceeded 2,000 ppm for several
million years.

Blames global warming for the resurgence of malaria in Kenya, even though several studies have found no climate link and attribute the problem to decreased spraying of homes with DDT and anti-malarial drug resistance.

Claims that 2004 set an all-time record for the number of tornadoes in the United States. Tornado frequency has not increased; rather, the detection of smaller tornadoes has increased. If we consider the tornadoes that have been detectable for many decades (category F-3 or greater), there actually has been a downward trend since 1950.

Cites Tuvalu, Polynesia, as a place where rising sea levels force residents to evacuate their homes. In reality, sea levels at Tuvalu fell during the latter half of the 20th century and even during the 1990s.

Neglects to mention that global warming could reduce the severity of winter stormsalso called frontal storms because their energy comes from colliding air masses (fronts)by decreasing the temperature differential between colliding air masses.

Ignores the large role of natural variability in Arctic climate, never mentioning either that Arctic temperatures during the 1930s equalled or exceeded those of the late 20th century, or that the Arctic during the early- to mid-Holocene was significantly warmer than it is today.

Ignores a study by University of Missouri professor Curt Davis that found an overall Antarctic ice mass gain during 1992-2003.

Neglects to mention that NASA satellites show an Antarctic cooling trend of 0.11C per decade since 1978.

Calls carbon dioxide the most important greenhouse gas. Water vapour and clouds are the leading contributors and account for over 70% of the greenhouse effect.

Claimed that ice cap on Mt. Kilimanjaro is disappearing due to global warming, though satellite measurements show no temperature change at the summit.

This is only a partial list of errors, omissions and exaggerations.

See here from the Competitive Enterprise Institute.
See here for an article listing 35 errors in AIT by Christopher Monckton of Brenchley.

The decision by the British government to distribute the film "An Inconvenient Truth" to schools has been the subject of a legal action. The British High Court found that the film was false or misleading in 11 respects.

In order for the film to be shown, the High Court ruled in October, 2007 that teachers must make it clear to their students that:
   1.) The film is a political work and promotes only one side of the argument.
   2.)  Nine inaccuracies have to be specifically drawn to the attention of school children.

The inaccuracies are listed here.

Al Gore and the IPCC shared the 2007 Nobel Peace Price "for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change". Irena Sendler was considered for the prize for saving 2500 children and infants from the Nazi Warsaw Ghetto and the extermination camps during World War II. She was not selected. See her story here.


Warnings of Global Cooling

Nigel Weiss, Professor Emeritus at the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge says that throughout earth's history climate change has been driven by factors other than man: "Variable behaviour of the sun is an obvious explanation," says Dr. Weiss, "and there is increasing evidence that Earth's climate responds to changing patterns of solar magnetic activity." The sun's most obvious magnetic features are sunspots, formed as magnetic fields rip through the sun's surface. "If you look back into the sun's past, you find that we live in a period of abnormally high solar activity," Dr. Weiss states. These hyperactive periods do not last long, "perhaps 50 to 100 years, then you get a crash," says Dr. Weiss. 'It's a boom-bust system, and I would expect a crash soon."
In addition to the 11-year cycle, sunspots almost entirely "crash," or die out, every 200 years or so as solar activity diminishes. When the crash occurs, the Earth can cool dramatically. These phenomenon, known as "Grand minima," have recurred over the past 10,000 years, if not longer. In the 17th century, sunspots almost completely disappeared for 70 years. That was the coldest interval of the Little Ice Age, when New York Harbour froze, allowing walkers to journey from Manhattan to Staten Island, and when Viking colonies abandoned Greenland, a once verdant land that became tundra.
In contrast, when the sun is very active, such as the period we're now in, the Earth can warm dramatically. This was the case during the Medieval Warm Period, when the Vikings first colonized Greenland and when Britain was wine-growing country.
No one knows precisely when a crash will occur but some expect it soon, because the sun's polar field is now at its weakest since measurements began in the early 1950s. Some predict the crash within five years, and many speculate about its effect on global warming. Several authorities are now warning of global cooling because the sun has entered a quiet period.

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