||"It's the sun"
In the last 35 years of global warming, sun and climate have been going in opposite directions
In the last 35 years of global warming, the sun has shown a slight cooling trend. Sun and climate have been going in opposite directions.
||"There is no consensus"
97% of climate experts agree humans are causing global warming.
That humans are causing global warming is the position of the Academies of Science from 19 countries plus many scientific organizations that study climate science. More specifically, around 95% of active climate researchers actively publishing climate papers endorse the consensus position.
||"Models are unreliable"
||Models successfully reproduce temperatures since 1900 globally, by land, in the air and the ocean.
||While there are uncertainties with climate models, they successfully reproduce the past and have made predictions that have been subsequently confirmed by observations.
||"Animals and plants can adapt"
||Global warming will cause mass extinctions of species that cannot adapt on short time scales.
||A large number of ancient mass extinction events have been strongly linked to global climate change. Because current climate change is so rapid, the way species typically adapt (eg - migration) is, in most cases, simply not be possible. Global change is simply too pervasive and occurring too rapidly.
||"Antarctica is gaining ice"
||Satellites measure Antarctica losing land ice at an accelerating rate.
||While the interior of East Antarctica is gaining land ice, overall Antarctica is losing land ice at an accelerating rate. Antarctic sea ice is growing despite a strongly warming Southern Ocean.
||"CO2 lags temperature"
||CO2 didn't initiate warming from past ice ages but it did amplify the warming.
||When the Earth comes out of an ice age, the warming is not initiated by CO2 but by changes in the Earth's orbit. The warming causes the oceans to give up CO2. The CO2 amplifies the warming and mixes through the atmosphere, spreading warming throughout the planet. So CO2 causes warming AND rising temperature causes CO2 rise.
||"We're heading into an ice age"
||Worry about global warming impacts in the next 100 years, not an ice age in over 10,000 years.
||The warming effect from more CO2 greatly outstrips the influence from changes in the Earth's orbit or solar activity, even if solar levels were to drop to Maunder Minimum levels.
||"Hockey stick is broken"
||Recent studies agree that recent global temperatures are unprecedented in the last 1000 years.
||Since the hockey stick paper in 1998, there have been a number of proxy studies analysing a variety of different sources including corals, stalagmites, tree rings, boreholes and ice cores. They all confirm the original hockey stick conclusion: the 20th century is the warmest in the last 1000 years and that warming was most dramatic after 1920.
||"Hurricanes aren't linked to global warming"
||There is increasing evidence that hurricanes are getting stronger due to global warming.
||It is unclear whether global warming is increasing hurricane frequency but there is increasing evidence that warming increases hurricane intensity.
||"Glaciers are growing"
||Most glaciers are retreating, posing a serious problem for millions who rely on glaciers for water.
||While there are isolated cases of growing glaciers, the overwhelming trend in glaciers worldwide is retreat. In fact, the global melt rate has been accelerating since the mid-1970s.
||"1934 - hottest year on record"
||1934 was one of the hottest years in the US, not globally.
||1934 is the hottest year on record in the USA which only comprises 2% of the globe. According to NASA temperature records, the hottest year on record globally is 2005.
||"Sea level rise is exaggerated"
||A variety of different measurements find steadily rising sea levels over the past century.
||Sea levels are measured by a variety of methods that show close agreement - sediment cores, tidal gauges, satellite measurements. What they find is sea level rise has been steadily accelerating over the past century.
||"Medieval Warm Period was warmer"
||Globally averaged temperature now is higher than global temperature in medieval times.
||While the Medieval Warm Period saw unusually warm temperatures in some regions, globally the planet was cooler than current conditions.
||"Arctic icemelt is a natural cycle"
||Thick arctic sea ice is undergoing a rapid retreat.
||Arctic sea ice has been retreating over the past 30 years. The rate of retreat is accelerating and in fact is exceeding most models' forecasts.
||"Oceans are cooling"
||The most recent ocean measurements show consistent warming.
||Early estimates of ocean heat from the Argo showed a cooling bias due to pressure sensor issues. Recent estimates of ocean heat that take this bias into account show continued warming of the upper ocean. This is confirmed by independent estimates of ocean heat as well as more comprehensive measurements of ocean heat down to 2000 metres deep.
||"IPCC is alarmist"
Numerous papers have documented how IPCC predictions are more likely to underestimate the climate response.
The IPCC lead authors are experts in their field, instructed to fairly represent the full range of the up-to-date, peer-reviewed literature. Consequently, the IPCC reports tend to be cautious in their conclusions. Comparisons to the most recent data consistently finds that climate change is occurring more rapidly and intensely than indicated by IPCC predictions.
||"Polar bear numbers are increasing"
||Polar bears are in danger of extinction as well as many other species.
||While there is some uncertainty on current polar bear population trends, one thing is certain. No sea ice means no seals which means no polar bears. With Arctic sea ice retreating at an accelerating rate, the polar bear is at grave risk of extinction
||"It's not happening"
There are many lines of evidence indicating global warming is unequivocal.
There are many lines of independent empirical evidence for global warming, from accelerated ice loss from the Arctic to Antarctica to the poleward migration of plant and animal species across the globe.
||"Greenland is gaining ice"
||Greenland on the whole is losing ice, as confirmed by satellite measurement.
||While the Greenland interior is in mass balance, the coastlines are losing ice. Overall Greenland is losing ice mass at an accelerating rate. From 2002 to 2009, the rate of ice mass loss doubled.
||"CO2 is plant food"
The effects of enhanced CO2 on terrestrial plants are variable and complex and dependent on numerous factors
The effects of enhanced CO2 on terrestrial plants are variable and complex and dependent on numerous factors
||"Arctic sea ice has recovered"
||Thick arctic sea ice is in rapid retreat.
||Arctic sea ice has been steadily thinning, even in the last few years while the surface ice (eg - sea ice extent) increased slightly. Consequently, the total amount of Arctic sea ice in 2008 and 2009 are the lowest on record.
||"There's no correlation between CO2 and temperature"
||There is long-term correlation between CO2 and global temperature; other effects are short-term.
||Even during a period of long term warming, there are short periods of cooling due to climate variability. Short term cooling over the last few years is largely due to a strong La Nina phase in the Pacific Ocean and a prolonged solar minimum.
||"It cooled mid-century"
||Mid-century cooling involved aerosols and is irrelevant for recent global warming.
||There are a number of forcings which affect climate (eg - stratospheric aerosols, solar variations). When all forcings are combined, they show good correlation to global temperature throughout the 20th century including the mid-century cooling period. However, for the last 35 years, the dominant forcing has been CO2.
||"CO2 was higher in the past"
When CO2 was higher in the past, the sun was cooler.
When CO2 levels were higher in the past, solar levels were also lower. The combined effect of sun and CO2 matches well with climate.
||"Satellites show no warming in the troposphere"
||The most recent satellite data show that the earth as a whole is warming.
||Satellite measurements match model results apart from in the tropics. There is uncertainty with the tropical data due to how various teams correct for satellite drift. The U.S. Climate Change Science Program concludes the discrepancy is most likely due to data errors.
||"2009-2010 winter saw record cold spells"
||A cold day in Chicago in winter has nothing to do with the trend of global warming.
||The cold snap is due to a strong phase of the Arctic Oscillation. This is causing cool temperatures at mid-latitudes (eg - Eurasia and North America) and warming in polar regions (Greenland and Arctic Ocean). The warm and cool regions roughly balance each other out with little impact on global temperature.
||"Mt. Kilimanjaro's ice loss is due to land use"
||Most glaciers are in rapid retreat worldwide, notwithstanding a few complicated cases.
||Mount Kilimanjaro's shrinking glacier is complicated and not due to just global warming. However, this does not mean the Earth is not warming. There is ample evidence that Earth's average temperature has increased in the past 100 years and the decline of mid- and high-latitude glaciers is a major piece of evidence.
||"It's a natural cycle"
||No known natural forcing fits the fingerprints of observed warming except anthropogenic greenhouse gases.
||A natural cycle requires a forcing, and no known forcing exists that fits the fingerprints of observed warming - except anthropogenic greenhouse gases.
||"It's Pacific Decadal Oscillation"
||The PDO shows no trend, and therefore the PDO is not responsible for the trend of global warming.
||PDO as an oscillation between positive and negative values shows no long term trend, while temperature shows a long term warming trend. When the PDO last switched to a cool phase, global temperatures were about 0.4C cooler than currently. The long term warming trend indicates the total energy in the Earth's climate system is increasing due to an energy imbalance.
||"IPCC were wrong about Himalayan glaciers"
Glaciers are in rapid retreat worldwide, despite 1 error in 1 paragraph in a 1000 page IPCC report.
The IPCC error on the 2035 prediction was unfortunate and it's important that such mistakes are avoided in future publications through more rigorous review. But the central message of the IPCC AR4, is confirmed by the peer reviewed literature. The Himalayan glaciers are of vital importance, providing drinking water to half a billion people. Satellites and on-site measurements are observing that Himalayan glaciers are disappearing at an accelerating rate.
||"2nd law of thermodynamics contradicts greenhouse theory"
||The 2nd law of thermodynamics is consistent with the greenhouse effect which is directly observed.
||The atmosphere of the Earth is less able to absorb shortwave radiation from the Sun than thermal radiation coming from the surface. The effect of this disparity is that thermal radiation escaping to space comes mostly from the cold upper atmosphere, while the surface is maintained at a substantially warmer temperature. This is called the "atmospheric greenhouse effect", and without it the Earth's surface would be much colder.
||"Sea level rise predictions are exaggerated"
||Sea level rise is now increasing faster than predicted due to unexpectedly rapid ice melting.
||Observed sea levels are actually tracking at the upper range of the IPCC projections. When accelerating ice loss from Greenland and Antarctica are factored into sea level projections, the estimated sea level rise by 2100 is between 75cm to 2 metres.
||"It's the ocean"
||The oceans are warming and moreover are becoming more acidic, threatening the food chain.
||Oceans are warming across the globe. In fact, globally oceans are accumulating energy at a rate of 4 x 1021 Joules per year - equivalent to 127,000 nuclear plants (which have an average output of 1 gigawatt) pouring their energy directly into the world's oceans. This tells us the planet is in energy imbalance - more energy is coming in than radiating back out to space.
||"Corals are resilient to bleaching"
||Globally about 1% of coral is dying out each year.
||On a world scale coral reefs are in decline. Over the last 30-40 years 80% of coral in the Caribbean have been destroyed and 50% in Indonesia and the Pacific. Bleaching associated with the 1982 -1983 El-Nino killed over 95% of coral in the Galapagos Islands and the 1997-1998 El-Nino alone wiped out 16% of all coral on the planet. Globally about 1% of coral is dying out each year.
||"CO2 effect is saturated"
||Direct measurements find that rising CO2 is trapping more heat.
||If the CO2 effect was saturated, adding more CO2 should add no additional greenhouse effect. However, satellite and surface measurements observe an enhanced greenhouse effect at the wavelengths that CO2 absorb energy. This is empirical proof that the CO2 effect is not saturated.
||Methane plays a minor role in global warming but could get much worse if permafrost starts to melt.
||While methane is a more potent greenhouse gas than CO2, there is over 200 times more CO2 in the atmosphere. Hence the amount of warming methane contributes is 28% of the warming CO2 contributes.
||"CO2 has a short residence time"
||Excess CO2 from human emissions has a long residence time of over 100 years
||Individual carbon dioxide molecules have a short life time of around 5 years in the atmosphere. However, when they leave the atmosphere, they're simply swapping places with carbon dioxide in the ocean. The final amount of extra CO2 that remains in the atmosphere stays there on a time scale of centuries.
||"Humidity is falling"
||Multiple lines of independent evidence indicate humidity is rising and provides positive feedback.
||To claim that humidity is decreasing requires you ignore a multitude of independent reanalyses that all show increasing humidity. It requires you accept a flawed reanalysis that even its own authors express caution about. It fails to explain how we can have short-term positive feedback and long-term negative feedback. In short, to insist that humidity is decreasing is to neglect the full body of evidence.
||"Springs aren't advancing"
||Hundreds of flowers across the UK are flowering earlier now than any time in 250 years.
||A synthesis of nearly 400,000 first flowering records covering 405 species across the UK found that British plants are flowering earlier now than at any time in the last 250 years.
||"It's land use"
||Land use plays a minor role in climate change, although carbon sequestration may help to mitigate.
||Correlations between warming and economic activity are most likely spurious. They don't take into account local forcing agents such as tropospheric ozone or black carbon. Correlations are likely over-estimated since grid boxes in both economic and climate data are not independent. Lastly, there is significant independent evidence for warming in the oceans, snow cover and sea ice extent changes.
||"CO2 is not increasing"
||CO2 is increasing rapidly, and is reaching levels not seen on the earth for millions of years.
||Currently, humans are emitting around 29 billion tonnes of carbon dioxide into the atmosphere per year. Around 43% remains in the atmosphere - this is called the 'airborne fraction'. The rest is absorbed by vegetation and the oceans. While there are questions over how much the airborne fraction is increasing, it is clear that the total amount of CO2 in the atmosphere is increasing dramatically. Current CO2 levels are the highest in 15 million years.
||"They changed the name from 'global warming' to 'climate change'"
'Global warming' and 'climate change' mean different things and have both been used for decades.
There have long been claims that some unspecificed "they" has "changed the name from 'global warming' to 'climate change'". In reality, the two terms mean different things, have both been used for decades, and the only individual to have specifically advocated changing the name in this fashion is a global warming 'skeptic'.
||"CO2 is coming from the ocean"
||The ocean is absorbing massive amounts of CO2, and is becoming more acidic as a result.
||Measurements of carbon isotopes and falling oxygen in the atmosphere show that rising carbon dioxide is due to the burning of fossil fuels and cannot be coming from the ocean.
||"CO2 is not the only driver of climate"
||Theory, models and direct measurement confirm CO2 is currently the main driver of climate change.
||While there are many drivers of climate, CO2 is the most dominant radiative forcing and is increasing faster than any other forcing.
||"Southern sea ice is increasing"
||Antarctic sea ice has grown in recent decades despite the Southern Ocean warming at the same time.
||Antarctic sea ice has growing over the last few decades but it certainly is not due to cooling - the Southern Ocean has shown warming over same period. Increasing southern sea ice is due to a combination of complex phenomena including cyclonic winds around Antarctica and changes in ocean circulation.
||"Lindzen and Choi find low climate sensitivity"
||Lindzen and Choi’s paper is viewed as unacceptably flawed by other climate scientists.
||Lindzen's analysis has several flaws, such as only looking at data in the tropics. A number of independent studies using near-global satellite data find positive feedback and high climate sensitivity.
||"Humans are too insignificant to affect global climate"
||Humans are small but powerful, and human CO2 emissions are causing global warming.
||Atmospheric CO2 levels are rising by 15 gigatonnes per year. Humans are emitting 26 gigatonnes of CO2 into the atmosphere. Humans are dramatically altering the composition of our climate.
||"It's too hard"
||Scientific studies have determined that current technology is sufficient to reduce greenhouse gas emissions enough to avoid dangerous climate change.
||The argument that solving the global warming problem by reducing human greenhouse gas emissions is "too hard" generally stems from the belief that (i) our technology is not sufficiently advanced to achieve significant emissions reductions, and/or (ii) that doing so would cripple the global economy. However, studies have determined that current technology is sufficient to reduce greenhouse gas emissions the necessary amount, and that we can do so without significant impact on the economy.
||"Tree-rings diverge from temperature after 1960"
||This is a detail that is complex, local, and irrelevant to the observed global warming trend.
||The divergence problem is a physical phenomenon - tree growth has slowed or declined in the last few decades, mostly in high northern latitudes. The divergence problem is unprecedented, unique to the last few decades, indicating its cause may be anthropogenic. The cause is likely to be a combination of local and global factors such as warming-induced drought and global dimming. Tree-ring proxy reconstructions are reliable before 1960, tracking closely with the instrumental record and other independent proxies.
||"Hansen's 1988 prediction was wrong"
Jim Hansen had several possible scenarios; his mid-level scenario B was right.
Subsequent comparison of observations with predictions find that Hansen's Scenario B (which most closely matched the level of CO2 emissions) shows close correlation with observed temperatures.
||"Earth hasn't warmed as much as expected"
||This argument ignores the cooling effect of aerosols and the planet's thermal inertia.
||The argument that "Earth hasn't warmed as much as expected" generally relies on ignoring the factors which have a cooling effect on the Earth's temperatures, and the planet's thermal inertia, which delays the full amount of global warming. When we do the calculations and include all radiative forcings and the amount of heat being absorbed by the oceans, it shows that the Earth has warmed almost exactly as much as we would expect.
||"It's a climate regime shift"
||There is no evidence that climate has chaotic “regimes” on a long-term basis.
||A full reading of Tsonis and Swanson's research shows that internal variability from climate shifts merely cause temporary slow downs or speeding up of the long-term warming trend. When the internal variability is removed from the temperature record, what we find is nearly monotonic, accelerating warming throughout the 20th Century.
||"Less than half of published scientists endorse global warming"
||Around 97% of climate experts agree that humans are causing global warming.
||Schulte's paper makes much of the fact that 48% of the papers they surveyed are neutral papers, refusing to either accept or reject anthropogenic global warming. The fact that so many studies on climate change don't bother to endorse the consensus position is significant because scientists have largely moved from what's causing global warming onto discussing details of the problem (eg - how fast, how soon, impacts, etc).
||"Ice isn't melting"
Arctic sea ice has shrunk by an area equal to Western Australia, and summer or multi-year sea ice might be all gone within a decade.
Ice mass loss is occuring at an accelerated rate in Greenland, Antarctica and globally from inland glaciers. Arctic sea ice is also falling at an accelerated rate. The exception to this ice loss is Antarctic sea ice which has been growing despite the warming Southern Ocean. This is due to local factors unique to the area.
||"Climate is chaotic and cannot be predicted"
||Weather is chaotic but climate is driven by Earth's energy imbalance, which is more predictable.
||Weather is chaotic because air is light, it has low friction and viscosity, it expands strongly when in contact with hot surfaces and it conducts heat poorly. Therefore weather is never in equilibrium and the wind always blows. The climate is mostly explained by equilibrium radiation physics, which puts the brakes on variations in global temperatures. Effects from weather, the Sun, volcanoes etc. currently only causes a small amount of chaotic behavior compared to the deterministic, predictable greenhouse gas forcing for the next 100 years"
||"Freedom of Information (FOI) requests were ignored"
||An independent inquiry found CRU is a small research unit with limited resources and their rigour and honesty are not in doubt.
||The Independent Climate Change Email Review found the CRU scientists were unhelpful and unsympathetic to information requesters and at times broke FoI laws. However, CRU is a small research unit with limited resources, and they perceived the requesters were not acting in good faith. The same inquiry found the rigour and honesty of the scientists are not in doubt, and their behaviour did not prejudice the advice given to policymakers.
||"Tuvalu sea level isn't rising"
||Tuvalu sea level is rising 3 times larger than the global average.
||Between 1950-2009 sea level at Tuvalu rose at the rate of 5.1 (±0.7) mm per year. This is almost 3 times larger than average global sea level rise over the same period.
||"Renewables can't provide baseload power"
A number of renewable sources already do provide baseload power, and we don't need renewables to provide a large percentage of baseload power immediately.
Although renewable energy does not necessarily need to provide baseload power in the short-term, there are several ways in which it can do so. For example, geothermal energy is available at all times, concentrated solar thermal energy has storage capability, and wind energy can be stored in compressed air.
||"Ice Sheet losses are overestimated"
||A number of independent measurements find extensive ice loss from Antarctica and Greenland.
||Wu et al (2010) use a new method to calculate ice sheet mass balance. This method, like all new methods will improve and be revised with time. Although, it does not agree well with most other measurement techniques, Wu et al's (2010) estimate is still at the upper end of IPCC predictions for ice losses and shows extensive land-ice losses from both Antarctica and Greenland.
||"Melting ice isn't warming the Arctic"
||Melting ice leads to more sunlight being absorbed by water, thus heating the Arctic.
||Decline in sea ice is the major driver of Arctic amplification. This is evidence by the pattern of atmospheric warming over the Arctic. Maximum warming occurs over the surface during winter while less surface warming is found in summer when heat is being used to melt sea ice. This pattern is consistent with sea ice amplification.
||"Satellite error inflated Great Lakes temperatures"
||Temperature errors in the Great Lakes region are not used in any global temperature records.
||Temperature errors in the Great Lakes region are not incorporated in any of the global mean temperature records. In particular, there is no connection to the satellite microwave temperature analyses by RSS and UAH, which use entirely different sensors operating in a quite different portion of the electromagnetic spectrum.
||"We're heading into cooling"
||There is no scientific basis for claims that the planet will begin to cool in the near future.
||Claims have recently surfaced in the blogosphere that an increasing number of scientists are warning of an imminent global cooling, some even going so far as to call it a "growing consensus". There are two major flaws in these blog articles, (i) there is no scientific basis for claims that the planet will begin to cool in the near future, and (ii) many of the listed scientists are not predicting global cooling.
||"Most of the last 10,000 years were warmer"
||This argument uses regional temperature data that ends in 1855, long before modern global warming began.
||This argument uses temperatures from the top of the Greenland ice sheet. This data ends in 1855, long before modern global warming began. It also reflects regional Greenland warming, not global warming.
||"The sun is getting hotter"
||The sun has just had the deepest solar minimum in 100 years.
||Various independent measurements of solar activity all confirm the sun has shown a slight cooling trend since 1978.
||"Water vapor in the stratosphere stopped global warming"
||This possibility just means that future global warming could be even worse.
||The effect from stratospheric water vapor contributes a fraction of the temperature change imposed from man-made greenhouse gases. Also, it's not yet clear whether changes in stratospheric water vapor are caused by a climate feedback or internal variability (eg - linked to El Nino Southern Oscillation). However, the long term warming trend seems to speak against the possibility of a negative feedback.
||"An exponential increase in CO2 will result in a linear increase in temperature"
||CO2 levels are rising so fast that unless we decrease emissions, global warming will accelerate this century.
||Despite the logarithmic relationship between CO2 and surface temperatures, atmospheric CO2 levels are rising so fast that unless we dramatically decrease our emissions, global warming will accelerate over the 21st Century.
||"Mauna Loa is a volcano"
||The global trend is calculated from hundreds of CO2 measuring stations and confirmed by satellites.
||The trend in CO2 at Mauna Loa is practically identical to the global trend because CO2 mixes well throughout the atmosphere. The global trend is calculated from hundreds of CO2 measuring stations and is consistent with independently measurements from satellites.
||"Water levels correlate with sunspots"
||This detail is irrelevant to the observation of global warming caused by humans.
||There seems to be evidence for a link between solar activity and water levels. However, more direct comparisons between solar activity and global temperature finds that as the sun grew hotter or cooler, Earth's climate followed it with a 10 year lag - presumably due to the dampening effect of the ocean. Also found was that the correlation between solar activity and global temperatures ended around 1975, hence recent warming must have some other cause than solar variations.
||"Positive feedback means runaway warming"
||Positive feedback won't lead to runaway warming; diminishing returns on feedback cycles limit the amplification.
||Positive feedback means that a system reacts to a stimulus by reinforcing that stimulus, so the stimulus builds up, and the output builds up, and the stimulus builds up... However, this only leads to a "runaway" instability if the reinforcement is strong enough. If it's not, as in the case with the enhanced greenhouse effect, the feedback can give rise to a definite, but stable, increase over the original stimulus.
||"CO2 was higher in the late Ordovician"
||The sun was much cooler during the Ordovician.
||During the Ordovician, solar output was much lower than current levels. Consequently, CO2 levels only needed to fall below 3000 parts per million for glaciation to be possible. The latest CO2 data calculated from sediment cores show that CO2 levels fell sharply during the late Ordovician due to high rock weathering removing CO2 from the air. Thus the CO2 record during the late Ordovician is entirely consistent with the notion that CO2 is a strong driver of climate.
||"Scientists retracted claim that sea levels are rising"
||The Siddall 2009 paper was retracted because its predicted sea level rise was too low.
||The retracted paper actually predicts a low range of future sea level rise. The retraction removes a lower bound of sea level prediction. This increases confidence in other peer-reviewed research predicting sea level rise of 80cm to 2 metres by 2100.
||"Greenland has only lost a tiny fraction of its ice mass"
||Greenland's ice loss is accelerating & will add metres of sea level rise in upcoming centuries.
||Multiple lines of evidence indicate Greenland's ice loss is accelerating and will contribute sea level rise in the order of metres over the next few centuries.
||"Royal Society embraces skepticism"
||The Royal Society still strongly state that human activity is the dominant cause of global warming.
||The Royal Society states that "There is strong evidence that changes in greenhouse gas concentrations due to human activity are the dominant cause of the global warming that has taken place over the last half century" and "The decade 2000-2009 was, globally, around 0.15 °C warmer than the decade 1990-1999". They are not denying anthropogenic global warming.
||"97% consensus on human-caused global warming has been disproven"
The 97% consensus has been independently confirmed by a number of different approaches and lines of evidence.
The 97% consensus has been independently confirmed by a 2009 survey of Earth scientists, a 2011 analysis of public statements by climate scientists and analysis of peer-reviewed climate research.
||"CO2 only causes 35% of global warming"
CO2 and corresponding water vapor feedback are the biggest cause of global warming.
The Nature commentary by Penner et al. on which this argument is based actually says that on top of the global warming caused by carbon dioxide, other short-lived pollutants (such as methane and black carbon) cause an additional warming approximately 65% as much as CO2, and other short-lived pollutants (such as aerosols) also cause some cooling. However, claiming that CO2 has only caused 35% of global warming is a gross misinterpretation and misunderstanding of the paper.
||"Arctic sea ice extent was lower in the past"
Current Arctic sea ice extent is the lowest in the past several thousand years.
While there have been times in the distant past when Arctic sea ice extent was lower than today's, the current sea ice extent is the lowest in the past several thousand years.
||"Loehle and Scafetta find a 60 year cycle causing global warming"
||Loehle and Scafetta's paper is nothing more than a curve fitting exercise with no physical basis using an overly simplistic model.