Tag Archives: atmosphere

We’re doomed

The following post contains material of a depressing nature, and is unsuitable for readers under 65 years of age. Reader discretion is advised.

First point – the global climate is changing. Not many people dispute that any more. The mean global temperature has risen by 0.8°C over the past century, and the ten warmest years on record have all occurred since 1998. Within the past century many significant climate changes have been measured and reported, including increases in the frequency of heat waves in the U.S., an increasing proportion of precipitation coming in the form of intense, flood-inducing events, an increase in tropical cyclone intensity in the Atlantic Ocean, Caribbean, and Gulf of Mexico, a huge decrease in the seasonal extent of Arctic sea ice, and a big jump in the rate at which glaciers are melting.

The rates of change seem to be accelerating and most of the profound secondary changes are negative. Dr James Hansen, the NASA scientist who first drew international attention to the impending climate disaster, testified way back in 1988 that Earth had entered a long-term warming trend. Today the effects of global warming on the extremes of the global water cycle – stronger droughts and forest fires on the one hand, and heavier rains and floods on the other – have become more evident in Australia, Europe, North America, Africa and Asia.

Second point – the causal factors of climate change are now very well known. Earth is surrounded by a relatively thin layer of greenhouse gases – water vapour, carbon dioxide (CO2), methane and nitrous oxide – which act as a thermal blanket. About half the incoming solar radiation passes through the atmosphere to the Earth’s surface where some is absorbed and the remainder reflected back into the atmosphere. Substantial amounts of the energy absorbed are again radiated outward in the form of infrared heat. These contribute further to the warming of the atmosphere.

Third point – humanity has drastically changed global climatic dynamics by adding huge amounts of CO2, methane, nitrous oxide and chlorofluorocarbons to the atmosphere. Activities such as deforestation, land use changes and the burning of fossil fuels have increased atmospheric CO2 by a third since the Industrial Revolution began. Decomposition of wastes in landfills, burgeoning agriculture, especially rice cultivation, and huge populations of burping and manure-producing domestic livestock have boosted the amounts of methane in the atmosphere by a factor of three since the industrial revolution. Methane is twenty times more active than CO2 in atmospheric heat retention.

The atmospheric concentration of CO2 measured at the Mauna Loa Observatory in Hawaii is a good indicator of where we are now globally in respect of atmospheric change. Back in 1959 when the data collection programme was initiated by the National Oceanic and Atmospheric Administration (NOAA) the CO2 level was measured at 316 parts per million (ppm) and the annual increase was less than 1 ppm. Today the level is over 392 ppm and the annual increases are 2.2 ppm and getting larger all the time.

James Hansen and his climate scientist colleagues concluded that we have either reached, or are very close to, a set of climate “tipping points”. That means that climatic changes are now at a point where the feedbacks from changes spur even larger and more rapid further changes. Hansen cites Arctic sea ice as a good example of this. Global warming has initiated faster sea ice melt and has exposed darker ocean surfaces that absorb more sunlight which leads to more melting of ice. As a result, and without any additional greenhouse gases, the Arctic could soon be ice-free in the summer. The western Antarctic and Greenland ice sheets are vulnerable to even small additional warming – once disintegration gets well under way it will become unstoppable.

Pause for reality check – not only is climatic change a reality, it is progressing at an accelerating rate, the negative consequence are getting greater, and the likelihood of us managing to slow or reverse the negative trends are getting smaller.

Fourth point – James Hansen and his fellow climate scientists looked at the atmospheric CO2 levels, then at the changes in climate which were occurring, and came up with the recommendation that a CO2 level of 350 ppm (last recorded back in 1987) was pretty much the upper allowable limit if massive climatic related adverse effects were to be avoided. The number 350 has a certain appealing ring to it, and has been widely adapted by environmental organizations such as Bill McKibben’s 350.org as a universal target for citizen and government action on carbon emissions. The protagonists are quite aware that the present global atmospheric CO2 level has already overshot that target by more than 40 ppm, but they argue, convincingly, that a reversal is absolutely essential to safeguard our long-term global future.

Fifth point – and now we’re at the crux of the problem. How on Earth, or anywhere else for that matter, do we get anywhere close to reducing the rate at which atmospheric CO2 increases in future, never mind actually reversing the trend towards 350 ppm?

We think of Earth’s carbon reservoirs as being great fields of coal and petroleum compounds, which are more or less stable until we dig them up and burn them. But the globe’s biggest carbon reservoirs are in the atmosphere, the ocean, living ecosystems and soils, and are highly dynamic. They all exchange CO2 with the atmosphere, they both absorb it (oceans) and assimilate it (ecosystems), and they release it (oceans) or respire it (ecosystems). The critical point is that anthropogenic carbon emitted into the atmosphere is not destroyed but adds to the stockpile and is redistributed among the other carbon reservoirs. The turnover times range from years or decades (living plants) to millennia (the deep sea, soil). The bottom line is that any carbon released into the atmosphere is going to be around for a long, long time. Up to 1000 years in fact.

Sixth point – so how do we get from our present scene of 390 ppm CO2 in the atmosphere and impending climate doom to something closer to 350 ppm and a more stable climate scenario? Straight answer – we cannot. We simply don’t have that option.

Seventh point – the absolutely best case scenario for reduction of CO2 emissions to the atmosphere would be an immediate halt to all activities leading to anthropogenic carbon emissions. Park all motor vehicles, no more home heating, no coal-fired power plants, no burning of natural gas, no aircraft flying overhead, shoot and bury 90% of all domestic livestock. Just shut down all of human civilization. No more anthropogenic carbon emissions. Would this sacrifice bring the CO2 level down in a hurry?

Dr Susan Solomon and her colleagues at NOAA, with the help of their sophisticate computer models have addressed that very question. They ran a coupled climate–carbon cycle model which has components representing the dynamic ocean, the atmospheric energy–moisture interaction, and interactive sub-models of marine and terrestrial carbon cycles. The model reveals, sadly for us, that climate change is largely irreversible for 1000 years after all carbon emissions cease. The drop in radiative forcing of atmospheric CO2 (i.e. the extent to which CO2 causes atmospheric warming) is largely compensated by slower loss of heat to the oceans. So atmospheric temperatures do not drop significantly for at least 1,000 years. And the natural interactive processes between the atmosphere, ocean and ecosystems would carry on. Atmospheric CO2 concentration would eventually drop back to 350 ppm by about 2060 and then flatten out to near 300 ppm for the rest of the 1000 years.

Eighth point – I haven’t noticed any great urges on the part of ourselves to go and huddle in caves and gnaw on pine nuts and raw fish (no wood-burning allowed) to make this scenario work, so what is more likely?

Global carbon emissions from fossil fuel use were 6.2 billion tonnes back in 1990 when global CO2 was near 355 ppm. The 2010 estimate is 8.5 billion tonnes. That’s a 38 % increase over the levels used to formulate the Kyoto Agreement. The annual growth rate of emissions derived from fossil fuels is now about 3.5%, an almost four-fold increase from the 0.9% per year for the 1990-1999 period. Carbon emissions from land-use change (i.e. mainly deforestation) in 2007 (in just that one year) were estimated at 1.5 billion tonnes of carbon. The biggest increase in emissions has taken place in developing countries, largely in China and India, while developed countries have been growing slower. The largest regional shift has been that China passed the U.S. in 2006 to become the largest CO2 emitter, and India will soon overtake Russia to become the third largest emitter. Currently, more than half of the global emissions come from less developed countries. Developing countries with 80% of the world’s population still account for only 20% of the cumulative emissions since 1751. There is nowhere for these rates to go, other than up.

When the Intergovernmental Panel on Climate Change produced their Fourth Assessment Report in 2007, they diplomatically tried to hedge their bets. So they churned out 40 different scenarios based on emissions scenarios for the decade 2000-2010 which encompassed the full range of uncertainties related to future carbon emissions, demographic, social and economic inputs and possible future technological developments. The model predictions were correspondingly wide, ranging from “best” to “worst” in terms of atmospheric CO2 levels and changes in the associated climatic driving forces. Now it has become apparent that the actual emissions growth rate for 2000-2007 has exceeded the highest forecasted growth rates for 2000-2010 in their emissions scenarios.

Ninth point – so the most likely future outcomes (by the end of the century) are those at the top end of the scale outputted by the computer models (diagram above). That is to say our grandchildren will be looking at CO2 levels above 900 ppm, mean global temperature rises of 5 or 6 degrees C over what they are today, and an average sea level rise above 0.5 metres. Plus all the storms, cyclones, droughts, floods, vanishing shorelines, water wars and famines that might creep in along the way.

The end – CO2 concentrations in the atmosphere and future temperatures are just numbers, and pretty much the only things that computer models can output. We will have to estimate the extent of global human misery by ourselves.

An elder’s guide to climate scepticism

by Stan Hirst 

The other elders may drive me from the village with brooms and pitchforks when they read my confession. But the truth must out. I am, alas, a sceptic.

I am sceptical, as well as skeptical, that my beloved Earth is going to self-destruct on 31 December 2012. I think it’s more likely the Mayans ran out of wild fig bark on which they were drawing their calendars. I am sceptical that I am by nature diplomatic, charming and easygoing because Jupiter was hanging out with Venus in the Fourth House of the night sky right about the time I came into the world seventy-odd years ago. I am sceptical that the people responsible for the multi-billion dollar homeopathic remedy business have never learned to spell the words p-l-a-c-e-b-o and g-u-l-l-i-b-i-l-i-t-y. And all this scepticism flies in the teeth of the billions of people worldwide who buy into this stuff.

We sceptics are in good company. Albert Einstein was one.  In 1933 he famously stated that black holes do not and cannot exist. He couldn’t see one and couldn’t find the rationale for them in his famous equations. Today his successors have no such problems and not only think they have identified nearly 30 black hole candidates in the Milky Way galaxy but are now getting the proof that the holes behave in the relativistic way that Einstein’s theories predict.

But I’m concerned that we genuine sceptics are being given a bad name by all these so-called climate change and global warming sceptics out there.

We need to address a few issues to sort out these guys in the black hats. Firstly, what exactly is a sceptic? What is climate? And what is climate change and what does it entail?

The Oxford English Dictionary defines a sceptic as one who maintains a doubting attitude with reference to some particular question or statement. Michael Schermer, the entertaining editor of Skeptic magazine enlarges the concept thus:  “Modern skepticism is embodied in the scientific method that involves gathering data to formulate and test naturalistic explanations for natural phenomena. All facts in science are provisional and subject to challenge, and therefore skepticism is a method leading to provisional conclusions. The key to skepticism is to continuously and vigorously apply the methods of science to navigate the treacherous straits between “know nothing” skepticism and “anything goes” credulity”.

And what is ‘climate’ and how does it differ from ‘weather’?

Weather is the state of the atmosphere at any given moment to the extent that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. The way the concept is used in daily life refers to day-to-day temperature and precipitation activity. By contrast climate is the term for the average atmospheric conditions over longer periods of time. The difference between the two creates major confusion for many.  “How the heck can it be global warming when we’re having record snowfalls in eastern Canada?

Which leads us to the obvious next question – what is the evidence for climate change?

Lots of prestigious institutions keep honest meteorological data and report their findings. At the national level, Environment Canada reports that the national average temperature for 2010 was 3.0°C above normal, which makes it the warmest year on record since nationwide records began in 1948. The previous warmest year was 1998, 2.5°C above normal. Four Canadian climate regions (Arctic Tundra, Arctic Mountains and Fiords, North-eastern Forest and Atlantic Canada) experienced their warmest year on record in 2010, and for six other climate regions the year was amongst 10 warmest recorded.  Southern Alberta and Saskatchewan were the only parts of the country with close to normal temperatures. Environment Canada’s national temperature departures table shows that of the ten warmest years, four have occurred within the last decade, and 13 of the last 20 years are listed among the 20 warmest.

At the international level, the Climatic Research Unit of the University of East Anglia has global land and marine surface temperature data dating back to 1850. The Unit reports that the years 2003, 2005 and 2010 have been the warmest on record. The mean global temperature has risen by 0.8°C over the past century. The World Meteorological Organization reports that the ten warmest years on record have all occurred since 1998.

The U.S. Environmental Protection Agency has carefully summarized all the salient indicators of climate change occurring within the past century. These include:

  • heat waves – the frequency of heat waves in the U.S. has risen steadily since 1970, and the area within the U.S. experi­encing heat waves has increased;
  • average precipitation has increased since 1901 at an average rate of more than 6 percent per century in the U.S. and nearly 2 percent per century worldwide;
  • heavy precipitation – in recent years, a higher percentage of precipitation in the U.S. has come in the form of intense single-day events; eight of the top 10 years for extreme one-day precipitation events have occurred since 1990;
  • tropical cyclone intensity in the Atlantic Ocean, Caribbean, and Gulf of Mexico has risen noticeably over the past 20 years; six of the 10 most active hurricane seasons have occurred since the mid-1990s; this increase is closely related to variations in sea surface temperature in the tropical Atlantic;
  • Arctic sea ice – September 2007 had the lowest ice coverage of any year on record, followed by 2008 and 2009; the extent of Arctic sea ice in 2009 was 24 percent below the 1979 to 2000 historical average;
  • glaciers around the world have generally shrunk since the 1960s, and the rate at which glaciers are melting has accelerated over the last decade; overall, glaciers worldwide have lost more than 8000 km3 of water since 1960;
  • lakes in the northern U.S. are freezing later and thawing earlier than they did in the 1800s and early 1900s; the length of time that lakes stay frozen has decreased at an average rate of one to two days per decade;
  • snow cover over North America has generally decreased since 1972 (although there has been much year-to-year variability); snow covered an average of 8 million km2 of North America during the years 2000 to 2008, compared with 8.8 million km2 during the 1970s.

So we honest sceptics have no issue with the evidence for global warming. Its incontrovertible. Not even Sarah Palin could refudiate it.

What about the evidence for anthropogenic inputs to global climate change? In other words, to what extent are human activities, specifically the emission of carbon dioxide, methane and other greenhouse gases, responsible for the global warming observed to date?

Total global green house gas emissions (expressed as carbon dioxide equivalents) are nearing 30 billion metric tonnes per year. As a result mean global atmospheric carbon dioxide concentration has gone from about 280 parts per million during pre-industrial times to more than 380 parts per million today. Earlier CO2 data were collected from ice-cores in eastern Antarctica and have been the subject of dispute by so-called climate sceptics, but the modern-day data come from state of the art instrumentation on Mauna Loa in Hawaii and are incontestable. From 1990 to 2008 the radiative forcing of all the greenhouse gases in the Earth’s atmosphere increased by about 26 percent, the rise in carbon dioxide concentrations accounting for approximately 80 percent of this increase.

It turns out that atmospheric CO2 is not homogeneous. Some of it contains carbon-12, the rest carbon-13 (one more neutron per atom than carbon-12). Green plants prefer carbon-12 in their photosynthetic reactions. When fossil fuels, which are derived from ancient plants, are burned, the carbon-12 is release into the atmosphere. Over time the continuous carbon-12 emissions change the atmospheric proportion of carbon-13 to carbon-12, and this proportion can be measured in corals and sea sponges. So not only have background levels of CO2 increased over the past century, they are directly linked to fossil fuel burning. And we honest sceptics are still cool with the concept.

Next question – is the extra anthropogenically-derived CO2 responsible for the observed warming trend? The so-called ‘greenhouse’ effect of CO2 is well-known, and can easily be measured in a laboratory. But it has also been measured globally over the past 30 years by satellite-mounted infrared sensors and found to be significant. Moreover, the amounts of global atmospheric downward long wave radiation over land surfaces measured from 1973 to 2008 have been examined and found to be significant in contributing to the global greenhouse effect.

The U.S. Protection Agency’s summary includes some biological indicators of long-term climate change in the U.S.:

  • the average length of the growing season in the lower 48 states has increased by about two weeks since the beginning of the 20th century; a particularly large and steady increase having occurred over the last 30 years;  the observed changes reflect earlier spring warming as well as later arrival of fall frosts, and the length of the growing season has increased more rapidly in the west than in the east.
  • plant hardiness zones have shifted northward since 1990, reflecting higher winter temperatures in most parts of the country; large portions of several states have warmed by at least one hardiness zone;
  • leaf and bloom dates of lilacs and honeysuck­les in the lower 48 states are now a few days earlier than in 1900s;
  • bird wintering ranges have shifted northward by an average of 56 km since 1966, with a few species shifting by several hundred kilometres; many bird species have moved their wintering grounds farther from the coast, consistent with rising inland temperatures.

So there you have it. Take all the scientific evidence available and it would be difficult indeed not to concur with the 97 out of 100 climate experts who think that humans are indeed causing global warming.

So, if the evidence satisfies the honest sceptics amongst us, i.e. those who take the time to seek out and evaluate the evidence and try their level best to come to an honest and defensible conclusions, why then is there a substantial body of opinion which holds countervailing views, i.e. that there is no warming or climate change (its all just natural variation), or that there is change but we ain’t responsible (its Mother Nature’s fault)?

That would be the subject of future postings from the Elders. It opens up the opportunity for some innovative taxonomy of climate change personalities, but I’ll leave the naming to others!

Climate change indicators

by Stan Hirst

The evidence of human influences on climate change has become increas­ingly clear and compelling over the last several decades There is now convincing evidence that human activities such as electricity pro­duction and transportation are adding to the concen­trations of greenhouse gases that are already naturally present in the atmosphere. These heat-trapping gases are now at record-high levels in the atmosphere com­pared with the recent and distant past.

The U.S. Environmental Protection Agency has recently published Climate Change Indicators in the United States to help the concerned public readers interpret a set of important indicators  for climate change. The report presents 24 indicators, each describing trends in some way related to the causes and effects of climate change. The indicators focus primarily on the United States, but in some cases global trends are presented in order to provide context or a basis for comparison.  The following is a brief summary of the report’s contents.

Greenhouse Gases

Global Greenhouse Gas Emissions. Worldwide, emissions of greenhouse gases from human activities increased by 26 percent from 1990 to 2005. Emissions of carbon dioxide, which account for nearly three-fourths of the total, increased by 31 percent over this period. The majority of the world’s emissions are associated with energy use.

Atmospheric Concentrations of Greenhouse Gases. Concentrations of carbon dioxide and other greenhouse gases in the atmosphere have risen substantially since the beginning of the industrial era. Almost all of this increase is attributable to human activities. Histori­cal measurements show that the current levels of many greenhouse gases are higher than any seen in thousands of years, even after accounting for natural fluctuations.

Climate Forcing. From 1990 to 2008, the radiative forcing of all the greenhouse gases in the Earth’s atmosphere increased by about 26 percent. The rise in carbon dioxide concentrations accounts for approximately 80 percent of this increase. Radiative forcing is a way to measure how substances such as greenhouse gases affect the amount of energy that is absorbed by the atmosphere – an increase in radiative forcing leads to warming while a decrease in forcing produces cool­ing.

Weather and Climate

U.S. and Global Temperature. Average temperatures have risen across the lower 48 states since 1901, with an increased rate of warming over the past 30 years. Parts of the North, the West, and Alaska have seen temperatures increase the most. Seven of the top 10 warmest years on record for the lower 48 states have occurred since 1990, and the last 10 five-year periods have been the warmest five-year periods on record. Average global temperatures show a similar trend, and 2000–2009 was the warmest decade on record worldwide.

Heat Waves. The frequency of heat waves in the United States decreased in the 1960s and 1970s, but has risen steadily since then. The percentage of the United States experi­encing heat waves has also increased. The most severe heat waves in U.S. history remain those that occurred during the “Dust Bowl” in the 1930s, although average temperatures have increased since then.

Drought. Over the period from 2001 through 2009, roughly 30 to 60 percent of the U.S. land area experienced drought conditions at any given time. However, the data for this indicator have not been collected for long enough to determine whether droughts are increasing or decreasing over time.

U.S. and Global Precipitation. Average precipitation has increased in the United States and worldwide. Since 1901, precipitation has increased at an average rate of more than 6 percent per century in the lower 48 states and nearly 2 percent per century worldwide. However, shifting weather patterns have caused certain areas, such as Hawaii and parts of the Southwest, to experience less precipitation than they used to.

Heavy Precipitation. In recent years, a higher percentage of precipitation in the United States has come in the form of intense single-day events. Eight of the top 10 years for extreme one-day precipitation events have occurred since 1990. The occurrence of ab­normally high annual precipitation totals has also increased.

Tropical Cyclone Intensity. The intensity of tropical storms in the Atlantic Ocean, Caribbean, and Gulf of Mexico did not exhibit a strong long-term trend for much of the 20th century, but has risen noticeably over the past 20 years. Six of the 10 most active hurricane seasons have occurred since the mid-1990s. This increase is closely related to variations in sea surface temperature in the tropical Atlantic.

Oceans

Ocean Heat. Several studies have shown that the amount of heat stored in the ocean has increased substantially since the 1950s. Ocean heat content not only determines sea surface temperature, but it also affects sea level and currents.

Sea Surface Temperature. The surface temperature of the world’s oceans increased over the 20th century. Even with some year-to-year variation, the overall increase is statisti­cally significant, and sea surface temperatures have been higher during the past three decades than at any other time since large-scale measurement began in the late 1800s.

Sea Level. When averaged over all the world’s oceans, sea level has increased at a rate of roughly six-tenths of an inch per decade since 1870. The rate of increase has accelerated in recent years to more than an inch per decade. Changes in sea level relative to the height of the land vary widely because the land itself moves. Along the U.S. coastline, sea level has risen the most relative to the land along the Mid-Atlantic coast and parts of the Gulf Coast. Sea level has decreased relative to the land in parts of Alaska and the Northwest.

Ocean Acidity. The ocean has become more acidic over the past 20 years, and studies suggest that the ocean is substantially more acidic now than it was a few centuries ago. Rising acidity is associated with increased levels of carbon dioxide dissolved in the water. Changes in acidity can affect sensitive organisms such as corals.

Snow & Ice

Arctic Sea Ice. Part of the Arctic Ocean stays frozen year-round. The area covered by ice is typically smallest in September, after the summer melting season. September 2007 had the least ice of any year on record, followed by 2008 and 2009. The extent of Arctic sea ice in 2009 was 24 percent below the 1979 to 2000 historical average.

Glaciers. Glaciers in the United States and around the world have generally shrunk since the 1960s, and the rate at which glaciers are melting appears to have accelerated over the last decade. Overall, glaciers worldwide have lost more than 2,000 cubic miles of water since 1960, which has contributed to the observed rise in sea level.

Lake Ice. Lakes in the northern United States generally appear to be freezing later and thawing earlier than they did in the 1800s and early 1900s. The length of time that lakes stay frozen has decreased at an average rate of one to two days per decade.

Snow Cover. The portion of North America covered by snow has generally decreased since 1972, although there has been much year-to-year variability. Snow covered an average of 3.18 million square miles of North America during the years 2000 to 2008, compared with 3.43 million square miles during the 1970s.

Snowpack. Between 1950 and 2000, the depth of snow on the ground in early spring decreased at most measurement sites in the western United States and Canada. Spring snowpack declined by more than 75 percent in some areas, but increased in a few others.

Society & Ecosystems

Heat-Related Deaths. Over the past three decades, more than 6,000 deaths across the United States were caused by heat-related illness such as heat stroke. However, consider­able year-to-year variability makes it difficult to determine long-term trends.

Length of Growing Season. The average length of the growing season in the lower 48 states has increased by about two weeks since the beginning of the 20th century. A particularly large and steady increase has occurred over the last 30 years. The observed changes reflect earlier spring warming as well as later arrival of fall frosts. The length of the growing season has increased more rapidly in the West than in the East.

Plant Hardiness Zones. Winter low temperatures are a major factor in determining which plants can survive in a particular area. Plant hardiness zones have shifted noticeably northward since 1990, reflecting higher winter temperatures in most parts of the country. Large portions of several states have warmed by at least one hardiness zone.

Leaf and Bloom Dates. The timing of natural events such as leaf growth and flower blooms are influenced by climate change. Observations of lilacs and honeysuck­les in the lower 48 states indicate that leaf growth is now occurring a few days earlier than it did in the early 1900s. Lilacs and honeysuckles are also blooming slightly earlier than in the past, but it is difficult to determine whether this change is statistically meaningful.

Bird Wintering Ranges. Some birds shift their range or alter their migration habits to adapt to changes in temperature or other environmental conditions. Long-term stud­ies have found that bird species in North America have shifted their wintering grounds northward by an average of 35 miles since 1966, with a few species shifting by several hundred miles. On average, bird species have also moved their wintering grounds farther from the coast, consistent with rising inland temperatures.