Global Warming and Climate Change Facts

Over the last 30 years of global warming, the sun has shown a slight cooling trend. Sun and climate are going in opposite directions. This has led a number of scientists independently concluding that the sun cannot be the cause of recent global warming.

One of the most common and persistent climate myths is that the sun is the cause. This argument is made by cherry picking the data - showing past periods when sun and climate move together but ignoring the last few decades when the two diverge.

Health

Warmer winters would mean fewer deaths, particularly among vulnerable groups like the aged. However, the same groups are also vulnerable to additional heat, and deaths attributable to heat waves are expected to be approximately five times as great as winter deaths prevented. It is widely believed that warmer climes will encourage migration of disease-bearing insects like mosquitoes and malaria is already appearing in places it hasn't been seen before.

Polar Melting

While the opening of a year-round ice free Arctic passage between the Atlantic and Pacific oceans would confer some commercial benefits, these are considerably outweighed by the negatives. Detrimental effects include loss of polar bear habitat and increased mobile ice hazards to shipping. The loss of ice albedo (the reflection of heat), causing the ocean to absorb more heat, is also a positive feedback; the warming waters increase glacier and Greenland ice cap melt, as well as raising the temperature of Arctic tundra, which then releases methane, a very potent greenhouse gas (methane is also released from the sea-bed, where it is trapped in ice-crystals called clathrates). Melting of the Antarctic ice shelves is predicted to add further to sea-level rise with no benefits accruing.

Ocean Acidification

A cause for considerable concern, there appear to be no benefits to the change in pH of the oceans. This process is caused by additional CO₂ being absorbed in the water, and may have severe destabilizing effects on the entire oceanic food-chain.

Melting Glaciers

The effects of glaciers melting are largely detrimental, the principle impact being that many millions of people (one-sixth of the world's population) depend on fresh water supplied each year by natural spring melt and regrowth cycles and those water supplies—drinking water, agriculture—may fail.

Sea Level Rise

Many parts of the world are low-lying and will be severely affected by modest sea rises. Rice paddies are being inundated with salt water, which destroys the crops. Seawater is contaminating rivers as it mixes with fresh water further upstream, and aquifers are becoming polluted. Given that the IPCC did not include melt-water from the Greenland and Antarctic ice-caps due to uncertainties at that time, estimates of sea-level rise are feared to considerably underestimate the scale of the problem. There are no proposed benefits to sea-level rise.

Environmental

Positive effects of climate change may include greener rain forests and enhanced plant growth in the Amazon, increased vegetation in northern latitudes and possible increases in plankton biomass in some parts of the ocean. Negative responses may include further growth of oxygen poor ocean zones, contamination or exhaustion of fresh water, increased incidence of natural fires, extensive vegetation die-off due to droughts, increased risk of coral extinction, decline in global photo-plankton, changes in migration patterns of birds and animals, changes in seasonal periodicity, disruption to food chains and species loss.

Economic

The economic impacts of climate change may be catastrophic, while there have been very few benefits projected at all. The Stern report made clear the overall pattern of economic distress, and while the specific numbers may be contested, the costs of climate change were far in excess of the costs of preventing it. Certain scenarios projected in the IPCC AR4 report would witness massive migration as low-lying countries were flooded. Disruptions to global trade, transport, energy supplies and labour markets, banking and finance, investment and insurance, would all wreak havoc on the stability of both developed and developing nations. Markets would endure increased volatility and institutional investors such as pension funds and insurance companies would experience considerable difficulty.

Developing countries, some of which are already embroiled in military conflict, may be drawn into larger and more protracted disputes over water, energy supplies or food, all of which may disrupt economic growth at a time when developing countries are beset by more egregious manifestations of climate change. It is widely accepted that the detrimental effects of climate change will be visited largely on the countries least equipped to adapt, socially or economically.

So a consensus in science is different from a political one. There is no vote. Scientists give up the debate because the sheer weight of consistent evidence is too compelling, the tide too strong to swim against any longer. Scientists change their minds on the basis of the evidence, and a consensus emerges over time. Not only do scientists stop debating, they also start relying on each others' work. All science depends on that which precedes it, and when one scientist builds on the work of another, he acknowledges the work of others through citations. The work that forms the foundation of climate change science is cited with great frequency by many other scientists, demonstrating that the theory is widely accepted and relied upon.

In the field of climate studies, which is informed by many different disciplines, the consensus is demonstrated by the number of scientists who have stopped debating what is causing climate change—and that's nearly all of them. A survey of all peer-reviewed papers on the subject "global climate change" published between 1993 and 2003 shows that not a single paper rejected the consensus position that global warming is man-made. 75% of the papers agreed with the consensus position while 25% made no comment either way, focusing on methods analysis instead (Oreskes 2004).

Several subsequent studies confirm that "...the debate on the authenticity of global warming and the role played by human activity is largely nonexistent among those who understand the nuances and scientific basis of long-term climate processes." (Doran 2009). In other words, more than 95% of scientists working in the disciplines contributing to studies of our climate, accept that climate change is almost certainly being caused by human activities.

We should also consider official scientific institutions and what they think about climate change. There are no national or major scientific institutions anywhere in the world that dispute the theory of anthropogenic climate change. Not one.

In the field of climate science, the consensus is unequivocal: human activities are causing climate change.

When looking for evidence of global warming, there are many different indicators that we should look for. While it's natural to start with air temperature, a more thorough examination should be as inclusive as possible: snow cover, ice melt, air temperature over land and sea, even the sea temperature itself. A 2010 study included 10 key indicators, and as shown above, every one of them is moving in the direction expected of a warming globe.

The question of global warming stopping is often raised in the when weather events that we don't typically associate with global warming happen—a big winter storm or drought-relieving rain. Global warming is entirely compatible with these events; after all, they are just weather. In climate change, it is the long-term trends that are important; measured over decades or more, and the long term trends show that the globe is still warming.

So all models are first tested in a process called "hindcasting." The models used to predict future global warming can accurately map past climate changes. If they get the past right, there is no reason to think their predictions would be wrong. Testing models against the existing instrumental record suggested CO₂ must cause global warming, because the models could not simulate what had already happened unless the extra CO₂ was added to the model. All other known forcings are adequate in explaining temperature variations prior to the rise in temperature over the last thirty years, while none of them are capable of explaining the rise in the past thirty years. CO₂ does explain that rise, and explains it completely without any need for additional, as yet unknown forcings.

Where models have been running for sufficient time, they have also been proved to make accurate predictions. For example, the eruption of Mt. Pinatubo allowed modelers to test the accuracy of models by feeding in the data about the eruption. The models successfully predicted the climatic response after the eruption. Models also correctly predicted other effects subsequently confirmed by observation, including greater warming in the Arctic and over land, greater warming at night, and stratospheric cooling.

The climate models, far from being alarmist, may be conservative in the predictions they produce. For example, here's a graph of sea level rise:

Sea level change; tide gauge data are indicated in red and satellite data in blue. The grey band shows the projections of the IPCC Third Assessment report (Copenhagen Diagnosis 2009).

Here, the models have understated the problem. In reality the events are all within the upper range of the model's predictions. There are other examples of models being too conservative, rather than alarmist as some portray them. All models have limits (uncertainties) for they are modeling chaotic systems. However, all models improve over time, and with increasing sources of real-world information such as satellites, the output of climate models can be constantly refined to increase their power and usefulness.

Climate models have already predicted many of the phenomena for which we now have empirical evidence. Climate models form a reliable guide to potential climate change.

More importantly, for the purpose of establishing a temperature trend, the relative level of single readings is less important than whether the pattern of all readings from all stations taken together is increasing, decreasing, or staying the same from year to year. Furthermore, since this question was first raised, research has established that any error that can be attributed to poor siting of weather stations is not enough to produce a significant variation in the overall warming trend being observed. Even groups that have recreated the global temperature record on their own, with the intent to prove that there are problems with the data, have admitted that there is no substance to the claim.

It's also vital to realize that climate change not based simply on ground level temperature records. Other, completely independent temperature data compiled from weather balloons, satellite measurements, and from sea and ocean temperature records, also tell a remarkably similar warming story.

Confidence in climate science depends on the correlation of many sets of these data from many different sources in order to produce conclusive evidence of a global trend.

A large number of ancient mass extinction events have indeed been strongly linked to global climate change, including the most sweeping die-off that ended the Palaeozoic Era, 250 million years ago, and the less cataclysmic Palaeocene-Eocene Thermal Maximum, 55 million years ago. These extinctions were natural, and there are a number of reasons why today's global change will have a particularly severe impact on biodiversity:

• Post-industrial man-made warming is already more rapid than anything the Earth has seen before, and it is expected to accelerate.
• An optimistic projection of future temperature is 2°C, which will shift the Earth's mean temperature into conditions which haven't existed since 3 million years ago. A more realistic projection, 4°C, will shift the Earth's climate back to the largely ice-free world that existed prior to 35 million years ago. When considering that the average species' "lifetime" is 1-3 million years, it easy to understand that our new climate will be unlike anything today's species have ever seen.
• Today's ecosystems have already been impacted by climate change. Most habitats are already degraded and their populations depleted by past human activities. For millennia our impacts have been localized although often severe, but during the last few centuries we have unleashed physical and biological transformations on a global scale. Feedbacks from global warming, ocean acidification, habitat loss, habitat fragmentation, invasive species, and chemical pollution will likely lead to cascading extinctions.
• Past adaptation to climate change by species was mainly through shifting their geographic range to higher or lower latitudes (depending on whether the climate was warming or cooling), or up and down mountain slopes. There were also evolutionary responses—individuals that were most tolerant to new conditions survived and so made future generations more intrinsically resilient. However, because of how fast the Earth is warming, and because of all the infrastructure humans have built (roads, railways, massive cities), time is up and there is nowhere for species to run or hide.

Though humans love record-breakers, they don't, on their own, tell us a much about trends, and it's trends that matter when monitoring Climate Change. Trends only appear by looking at all the data, globally, and taking into account other variables—like the effects of the El Nino ocean current or sunspot activity—not by cherry-picking single points.

There's also a tendency for some people just to concentrate on air temperatures when there are other, more useful, indicators that can perhaps give us a better idea how rapidly the world is warming. Oceans for instance, due to their immense size and heat storing capability, tend to give a much more 'steady' indication of the warming that is happening. Here records show that the Earth has been warming at a steady rate before and since 1998 and there's no signs of it slowing any time soon.

In Antarctica, sea ice grows quite extensively during winter but nearly completely melts away during the summer (see above). That is where the important difference between antarctic and arctic sea ice exists. Arctic sea ice lasts all the year round, there are increases during the winter months and decreases during the summer months but an ice cover does in fact remain in the North which includes quite a bit of ice from previous years (Figure 1). Essentially Arctic sea ice is more important for the earth's energy balance because when it melts, more sunlight is absorbed by the oceans whereas Antarctic sea ice normally melts each summer leaving the earth's energy balance largely unchanged.

One must also be careful how you interpret trends in Antarctic sea ice. Currently this ice is increasing and has been for years but is this the smoking gun against climate change? Not quite. Antarctic sea ice is gaining because of many different reasons but the most accepted recent explanations are listed below:

• Ozone levels over Antarctica have dropped causing stratospheric cooling and increasing winds which lead to more areas of open water that can be frozen (Gillet 2003, Thompson 2002, Turner 2009).
• The Southern Ocean is freshening because of increased rain, glacial run-off and snowfall. This changes the composition of the different layers in the ocean there causing less mixing between warm and cold layers and thus less melted sea ice (Zhang 2007).

All the sea ice talk aside, it is quite clear that really when it comes to Antarctic ice, sea ice is not the most important thing to measure. In Antarctica, the most important ice mass is the land ice sitting on the West Antarctic Ice Sheet and the East Antarctic Ice Sheet.

Estimates of recent changes in Antarctic land ice (see above) range from losing 100 gigatons/year to over 300 gigatons/year. Because 360 gigatons/year represents an annual sea level rise of 1 mm/year, recent estimates indicate a contribution of between 0.27 mm/year and 0.83 mm/year coming from Antarctica. There is of course uncertainty in the estimations methods but multiple different types of measurement techniques (explained here) all show the same thing, Antarctica is losing land ice as a whole, and these losses are accelerating quickly.