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Providing Insight
Into Climate Change
Climate Change Science Essay page 8

Effects of Warming

The IPCC and related groups have suggested several adverse effects of global warming. Real world data shows that these claims are mostly false. They ignore the huge benefits of warming and of CO2 emissions on plant growth.


      Sea Level Rise

The Permanent Service for Mean Sea Level is responsible for collecting and reporting of sea level data from the global network of tide gauges. This dataset includes 63 tide gauge records starting before 1950 and ending after 2015 which have more than 95% of the data. The graph below shows the running 20-year and 30-year trends of the average of the 63 tide gauge records. The missing data was linearly infilled and the seasonal signal was removed. The graph shows the 20-year and 30-year trend at December 2015 was 1.50 mm/yr and 1.30 mm/yr, respectively. The maximum 30-year trend was 1.34 mm/y ending November 1983.

Tide Gauge Sea Level Trends


The sea level has been rising since 1860 at about 2 mm/year to 2000 as shown below.
                   Sea Level Data

Sea level rise

Mean global sea level (gsl) (top), with its shaded 95% confidence interval, and mean gsl rate (bottom), with its shaded standard error interval. Adapted from Jevrejeva et al. (2006). See here from CO2science.

The IPCC AR4 estimates that "Global average sea level rose at an average rate of 1.8 [1.3 to 2.3] mm per year over 1961 to 2003. The rate was faster over 1993 to 2003, about 3.1 [2.4 to 3.8] mm per year." It also states "There is high confidence that the rate of observed sea level rise increased from the 19th to the 20th century."

Since August 1992 the satellite altimeters have been measuring sea level on a global basis. The University of Colorado at Boulder provides data from a series of satellites. Tide gauge calibrations are used to estimate altimeter drift.

Global sattellite Sea Level Rise

The global sea level rise with the seasonal signal removed is shown above. It shows a trend from 1992 thru January 2018 of 3.1 mm/year, which includes a glacial isostatic adjustment (GIA) of 0.3 mm/yr. The GIA is the effect of increasing ocean basin size. The sea level graph with GIA adjustment is what the sea level rise might have been IF the ocean basin size had not changed. The sea level rise with respect to land is 2.8 mm/yr. Below are graphs of global, Pacific ocean and Atlantic ocean sea level rise, all without GIA. The seasonal signal was removed from the global sea level data, but included in the Pacific and Altantic ocean data. The Atlantic trend is shown in two part due to the lower trend since 2003.

global sea level satellite

Pacific ocean sea level rise

Atlantic ocean sea level rise

Note that there has been a significant flattening of the trend since 2004. The global sea level rise since January 2004 of 2.62 mm/year is much less than the trend from 1992  to December 2003 of 3.23 mm/year. The trends since January 2004 of the Pacific and Atlantic oceans are 2.08 mm/year and 2.12 mm/year, respectively. The slowing of the sea level rise is consistent with the current lack of global warming.

The satellite SLR is greater than the global tide gauge SLR because the University of Colorado adds a dubious 0.9 mm/yr adjustment to the raw satellite measurements, which they claim is due to sensor drift.

Permanent Service for Mean Sea Level (PSMSL), here lists 10 tide gauge stations on the West coast of Canada with near continuous monthly data from 1973 through 2019.

Canada west coast sea level rise 10 tide gauges

The graph shows the average monthly sea level of 10 tide gauge stations on the West coast of Canada. The black line is the linear best fit to the data. Over the period 1973 to 2018 the average sea level has increased at 0.025 mm/year.

The Envisat is the newest and most sophisticated satellite to measure global sea level. Launched in 2002, Envisat is the largest Earth Observation spacecraft ever built. The data shows there has been no global sea level rise since the end of 2003.

Sea level from Envisat

Dr. Nils-Axel Morner, who has spent a lifetime in the study of sea levels, says There is a total absence of any recent acceleration in sea level rise as often claimed by IPCC and related groups.. Read his fascinating interview "Claim That Sea Level Is Rising Is a Total Fraud" June 22, 2007 EIR Economics 33.

Dr. Morner says the global sea level has been rising at 1.1 mm/year from 1850 to about 1940, then no increase to 1970. The IPCC uses a tide gauge in Hong Kong that shows 2.3 mm/year of sea level rise. The tide gauge is located where the land is known to be subsiding, so the record should not be used. Satellite altimetry data from the TOPEX/POSEIDON mission measures the sea level relative to the centre of the Earth (rather than relative to the coast) since 1992.

                        Satellite altimetry of TOPEX/POSEIDON

Satellite altimetry of TOPEX/POSEIDON


The graph above from Morner, 2004, shows the original satellite sea level data from 1992 to early 2000. Other than the effect of the 1997/98 El Nino, the data shows no sea level rise.

The satellite data shows no increase, but the IPCC adds a "correction factor" to the satellite data to make it agree with the tide gauge data at 2.3 mm/year. This data is presented as satellite data, but Morner says "it is a falsification of the data set".

                   Satellite Altimetry Data of TOPEX/POSEIDON Tilted Back to Original Level

Satellite Altimetry Data of TOPEX/POSEIDON Tilted Back to Original Level

The graph above from Morner, 2005, shows the satellite altimetry sea level data from 1993 to 2003 tilted back to the original level by excluding the tide-gauge factor. It shows variability around zero plus ENSO events.

See here for Dr. Morner's Memoradum paper, which was presented to the United Kingdom's House of Lords.

Satellite altimetry Topex/Poseidon data is adjusted by the University of Colorado for NASA to match the rate of sea level rise measured by a set of 64 tide gauges. Any difference between the raw satellite measurement and the tide gauge measurement is assumed to be the sum of satellite measurement drift error and the vertical land movement at the tide gauge location. A separate estimate of the land movement is made mainly by using "doppler orbitography and radiopositioning integrated by satellite" (DORIS) data at the tide gauge location. The raw satellite data is tilted by applying the satellite measurement drift as determined by the tide gauges. See here for a description of how satellite data is calibrated from a set of tide gauges.

Jason satellite sea level trend

The graph above shows the sea level trends from January 2002 to April 2011. Note that most of the sea level rise in this period is located in an area north of Australia. The average of five tide gauge stations' trends from the north coast of Australia using annual data is 17.7 mm/year from 2002 to 2009. However, the tropical Pacific ocean sea level was decreasing at up to 16 mm/year.

A famous tree in the Maldives shows no evidence of having been swept away by rising sea levels, as would be predicted by the global warming advocates. A group of Australian global-warming advocates came along and pulled the tree down, destroying the evidence that their theory was false.

The "INQUA Commission on Sea-Level Change and Coastal Evolution" led by Dr. Morner, prepared as estimate that the global sea level will rise 10 cm plus or minus 10 cm in the next 100 years. Dr. Morner has since revised his estimate to 5 cm per 100 years after considering data of the Sun activity suggesting that the warming trend may have ended and the Earth may be headed into a cooling trend.

It seems increasingly likely that a warming will increase precipitation and ice accumulation in the Polar Regions, and thus slow down or even reverse the ongoing sea level rise.
See "There is no alarming sea level rise!" here

The Proudman Oceanographic Laboratory estimates the rate of sea level rise at 1.42 plus or minus 0.14 mm/year for the period 1954 to 2003. This is less than the estimate of 1.91 plus or minus 0.14 mm/year for the period 1902 to 1953, indicating a slowing of the rate.
See here for an analysis of sea level rise by the Proudman Oceanographic Laboratory.  The following graph shows the rate of sea level change since 1905 using the highest quality long record tide gauges.

POL sea level

Comparison of the global mean rates of sea level change calculated from nine long-record stations with those calculated from 177 stations averaged into 13 regions. The shaded region indicates 1 S.E.  These records are from regions which do not experience high rates of Glacial Isostatic Adjustment (GIA) and which are not significantly affected by earthquakes. The comparison shows that over the common period of the two analyses (1955-1998) there is very strong agreement between the two global means.

Woppelmann et al used global positioning satellite (GPS) stations to correct tide gauge data for vertical land movements. In a 2007 paper, Wppelmann et al analyzed data from 160 GPS stations that were within 15 km of tide gauges to determine the vertical movement of the tide gauges. They determined that the global average sea-level rise from January 1999 to August 2005, after correcting the tide gauge data by the vertical land movement, was 1.31 +/- 0.30 mm/year. Note that this estimate is 58% less than the estimate reported (1993 - 2003) in the IPCC AR4. Seehere from World Climate Report archive, and the study abstract here.

The movie "An Inconvenient Truth" (AIT) suggests that the Antarctic ice sheet could melt, but in fact the temperature of Antarctica has been declining over the last 25 years by 0.11 Celsius per decade. There has been no significant melting during previous warm periods when temperatures were warmer than today.

               Antarctica Temperatures 1979 - 2009 MSU Data Set (Latitude -90 to -70)

Antarctica -70 to -85 MSU UAH

This graph was created from the MSU Data from

Antarctica ice sheet has been growing in thickness by 5 mm/year (1992 to 2003) according to a recent mass balance study. This net extraction of water from the global ocean, according to Wingham et al., occurs because "mass gains from accumulating snow, particularly on the Antarctic Peninsula and within East Antarctica, exceed the ice dynamic mass loss from West Antarctica."

A similar story is found in Greenland. The warmest period was not the last quarter century. Rather, as Vinther et al. report, "the warmest year in the extended Greenland temperature record was 1941, while the 1930s and 1940s were the warmest decades." In fact, their newly-lengthened record reveals there has been no net warming of the region over the last 75 years. A study of the Greenland ice sheet by Johannessen et al. 2005 found that below 1500 meters, the mean change of ice sheet height with time was a decline of 2.0 ± 0.9 cm/year, qualitatively in harmony with the statements of Alley et al.; but above 1500 meters, there was a positive growth rate of fully 6.4 ± 0.2 cm/year. Averaged over the entire ice sheet, the mean result was also positive, at a value of 5.4 ± 0.2 cm/year, which when adjusted for an isostatic uplift of about 0.5 cm/year yielded a mean growth rate of approximately 5 cm/year, for a total increase in the mean thickness of the Greenland Ice Sheet of about 55 cm over the 11-year period, which was primarily driven by accumulation of increased snowfall over the ice sheet.

A recent study by Zwally et al. 2005 found the Greenland ice sheet have experienced a net accumulation of ice which is producing a 0.03 +/- 0.01 mm/year decline in sea-level. See a review of this and several other studies on this topic.

A study by Dorthe Dahl-Jenson et al (2013) here presents data from the North Greenland Eemian Ice Drilling (NEEM) ice core that show only a modest ice-sheet response to the strong warming in the early Eemian. The paper reports that the "surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8±4 degrees Celsius above the mean of the past millennium. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400±250 metres, reaching surface elevations 122,000 years ago of 130±300 metres lower than the present." The lead author estimates that the melting during the Eemian could have only contributed 2 m of sea level rise. Dr. Patrick Michaels commenting of the paper here says the entire 6,000-year period averaged about 6°C warmer than the last 1000 years. The integrated heating during the Eemian (temperature change multiplied by time) was 36,000 degree-years. Climate models predict 3 C warming over Greenland by 2100, or 300 degree-years.  Michaels writes, "At that rate, it would take 12,000 years to just get rid of about one-eighth of the ice in this core."  The data suggests Greenland will contribute just 1.7 cm of sea level rise (2 m X 300/36000) by 2100 if the climate model temperature prediction is correct.


     Severe Weather

The IPCC claims that global warming will result in more severe weather. This doesn't make any sense, as most storms are caused by a difference in temperatures of colliding air masses. If CO2 warms the Polar Regions there will be smaller temperature differences, and less severe storms. All other things being equal, a warmer world should have fewer, not more, severe storms.

Unlike most storms, hurricanes are caused by difference in temperatures between the sea surface and the storm top.

Researchers Knutson and Tuleya examined a suite of climate models and found that they virtually unanimously projected that in a CO2-enhanced world, the middle and upper troposphere will warm at a faster rate than the surface, especially over the tropical oceans. More warming aloft than at the surface makes the atmosphere more stable and less conducive to storm formation. Thus, Knutson and Tuleya reported that the model-projected vertical stability increases in the future would temper (but not totally cancel out) the increase in storm intensity by rising sea surface temperature.

However, researchers Vecchi and Soden found that the climate models almost unanimously project that there will be an increase in the vertical wind shear during the hurricane season which also acts to inhibit tropical cyclone formation. The combined result is that any increase in hurricane intensity will be so small as to be undetectable. Incidentally, the actual vertical wind shear of Atlantic hurricanes have been declining since 1973, the opposite of the trend predicted by the climate models. See here.

There is absolutely no evidence of increasing severe storm events in the real world data.

For the North Atlantic as a whole, according to the World Meteorological Organization, "Reliable data ... since the 1940s indicate that the peak strength of the strongest hurricanes has not changed, and the mean maximum intensity of all hurricanes has decreased."

Gulev, et al (2000) employed NCEP/NCAR reanalysis data since 1958 to study the occurrence of winter storms over the northern hemisphere. They found a statistically significant (at the 95% level) decline of 1.2 cyclones per year for the period, during which temperatures reportedly rose in much of the hemisphere.

"Global warming causes increased storminess" makes for interesting headlines. It also violates fundamental scientific truth and the lessons of history.

Global hurricane activity declined to mid-2012 to levels not seen since 1978. The Accumulated Cyclone Energy (ACE) is the 2-year running sum of the combination of hurricanes' intensity and longevity. During the past 40 years, Global and Northern Hemisphere ACE undergoes significant variability but exhibits no significant statistical trend. The global 2013-02 ACE was 62% of the 1998-01 ACE. Tropical storm and hurricane data are from Weather Bell.

global ACE

The graph above shows the last 5-decades of Global and Northern Hemisphere ACE through Nov, 2020. Note that the year indicated represents the value of ACE through the previous 24-months for the Northern Hemisphere (bottom line/gray boxes) and the entire global (top line/blue boxes). The area in between represents the Southern Hemisphere total ACE.

TC frequency

The graph above shows the laheadst 4-decades of Global Hurricane and Global MajorHurricane frequency 12-month running sums through December, 2020. The top time series is the number of all hurricanes (maximum lifetime wind speed exceeds 64-knots). The bottom time series is the number of major hurricane strength (96-knots). The global frequency trend of all hurricanes indicates a small decline.

The northern hemisphere 2008 ACE was 85% of the 2005 ACE as shown in the stacked bar chart below.


Most thunderstorms occur in the tropics, but most tornatoes occur in the USA. Less than 1% of thunderstorms in the USA spawn tornadoes. Tornadoes requires directional wind shear, a change of wind direction with height. Wind shear occurs when cold and warm air masses collide. This never happens in the tropics so tornadoes never occur there. The graph below shows that the averate USA temperatures have increased since 1960 while the number of strong (F3 to F5) tornadoes have declined.  See here from Dr. Roy Spencer.

An outbreak of tornadoes in 2011 in the USA was caused by unseasonably cold spring weather. Dr. Spencer writes "An unusually warm Gulf of Mexico of 1 or 2 degrees right now cannot explain the increase in contrast between warm and cold air masses which is key for tornado formation because that slight warmth cannot compete with the 10 to 20 degree below-normal air in the Midwest and Ohio Valley which has not wanted to give way to spring yet. ... global warming causes FEWER tornado outbreaksnot more."

US tornadoes

NOAA presents a tornado information here. A graph of strong to severe tornadoes from 1954 to 2017 is shown below. It shows a significant declining trend. 2017 is tied with 1987 with the fewest F-3+ tornadoes since 1954.

US annual tornadoes F3+

A paper published in the Journal of Geography & Natural Disasters shows that "first half of the 20th century had more extreme weather than the second half". Several graphs of climate data are presented in support of this statement, including warming and cooling rates, temperature extremes, precipitation, and hurricanes making landfall in the USA. Global temperatures during the last few decades have been warmer than the first half of the 20th century. Many theoretical studies predict that a warming climate due to greenhouse gas emissions will produce more extreme weather. The paper states "The lack of public, political and policymaker appreciation of the disconnect between empirical data and theoretical constructs is profoundly worrying, especially in terms of policy advice being given." The hyperbole of predictions of extreme future weather may lead to excessive safety factors and over-adaptation. The author warns, "Over-adaptation that is not needed leaves clients free to sue advisors if the problems have been oversold and the costs of protection prove to have been excessive". The paper is here.

Dr. Indur M. Goklany prepared a study which examines whether losses due to such events (as measured by aggregate deaths and death rates) have increased globally and for the United States in recent decades. It puts these deaths and death rates into perspective by comparing them with the overall mortality burden, and briefly discuss what trends in these measures imply about human adaptive capacity. Globally, mortality and mortality rates have declined by 95 percent or more since the 1920s. The largest improvements came from declines in mortality due to droughts and floods, which apparently were responsible for 93 percent of all deaths caused by extreme events during the 20th Century. See here.

The most telling graph is the first one in the paper below:

global death rates - extreme events

The chart displays data on aggregate global mortality and mortality rates between 1900 and 2006 for the following weather-related extreme events: droughts, extreme temperatures (both extreme heat and extreme cold),floods, slides, waves and surges, wild fires and windstorms of different types (e.g., hurricanes, cyclones, tornados, typhoons, etc.). It indicates that both death and death rates have declined at least since the 1920s. Specifically, comparing the 1920s to the 2000 - 2006 period, the annual number of deaths declined from 485,200 to 22,100 (a 95 percent decline), while the death rate per million dropped from 241.8 to 3.5 (a decline of 99 percent).

Researchers analyzed 7,000 years of data from sediment cores from southern France's coastal region and found that severe storms were more frequent during global cooling, including The Little Ice Age, than during global warming periods, such as the Medieval Warming Period. See here.

The IPCC suggests that warming might result is more floods and draughts. There is no reason why a warmer world would have more floods and draughts. There is no trend of increasing floods or draughts. The Palmer Dought Index maintained by NOAA shows no trend in either floods or droughts in the USA as shown below.

 US drought

The 1930's and 1950's were very dry in the USA. We are fortunate that climate is so much better now.

Pederson et al. found that droughts during the end of the Little Ice Age were more severe and of longer duration than those of the 20th and 21st centuries. Cooler climates produced more extreme conditions in many parts of the world. See here.

Woodhouse et al. published a 1,200 year perspective of Southwestern North America droughts: "The medieval period was characterized by widespread and regionally severe, sustained drought in western North America. Proxy data documenting drought indicate centuries-long periods of increased aridity across the central and western U.S...The recent drought, thus far, pales hydrologically in comparison.". See here.

The graph below shows the proportion of the planet in drought, by intensity, 1982-2012. The graph is from the Global Integrated Drought Monitoring and Prediction System (GIDMaPS), which provides drought information based on multiple drought indicators. The system provides meteorological and agricultural drought information based on multiple satellites, and model-based precipitation and soil moisture data sets. The Do is mild drought, D1 is moderate drought, D2 and D3 are increasing severity, D4 is extreme drought. There is a slight declining trend of total droughts throughout the period. See here.

Solar activity was high during both the Medieval and modern periods. High solar energy can result in periods of more intense drought and they have nothing to do with CO2 emissions.


      Warming is Good for Your Health

The health benefits of a warmer planet are many times greater than any harmful effect. The positive health effects of heat have been well documented over the past quarter century.  The early studies of Bull (1973) and Bull and Morton (1975a,b) in England and Wales, for example, demonstrated that even normal changes in temperature are typically associated with inverse changes in death rates, especially in older people.  That is, when temperatures rise, death rates fall, while when temperatures fall, death rates rise.

Speculations on the potential impact of continued warming on human health often focus on mosquito-borne diseases. Elementary models suggest that higher global temperatures will enhance their transmission rates and extend their geographic ranges. However the histories of three such diseases - malaria, yellow fever, and dengue - reveal that climate has rarely been the principal determinant of their prevalence or range. Human activities and their impact on local ecology have generally been much more significant. It is therefore inappropriate to use climate-based models to predict future prevalence.

Dr. Benny Peiser write, "In Europe and Russia alone, more than 100,00 people die on average each year as a result of cold temperatures during the winter months." He says that modern societies have become much more resilient to climate extremes due to access to air conditioning and improved health care.

Dr. Peiser writes, "Britain’s leading medical experts have calculated that a rise of the average temperature by two degrees Celsius over the next 50 years would increase heat-related deaths in Britain by about 2,000 – but would reduce cold-related deaths by about 20,000. In other words, the decrease in the number of cold-related deaths would be much more significant (by a factor of 10) than the heat-related deaths due to rising temperatures. The potentially huge health benefits of moderate temperature increases have been confirmed by other researchers. They estimate that a warming of 2.5 degree Celsius would lower the annual death rate by 40,000 in the USA alone while reducing medical cost by almost $20 billion per year." see here.

 Statistics Canada reports deaths by month. The graph below shows the deaths per day for each month in Canada averaged over the years 2007 - 2011.

Death rate in Canada by month

The graph shows that the death rate in January is more than 100 deaths/day greater than in August. Cold related illnesses llike the flu, accidents on icy roads make winter a dangerous time.

         Agriculture and Climate Change

A small temperature drop would decrease the length of the growing season and cause a severe drop in the arable area in northern climates.  Conversley, warming would lengthen the growing season and increase the area suitable for agriculture.

The map below shows the present principal area of Canadian wheat production, and the reduction that would result from one and 2 degrees Celsius decreases in average surface temperature.

area of Canadian wheat production vs temperature


US Corn, wheat and rice yields have increased with temperatures. Corn yields have gone up 130% since 1960, see here.

The graph below shows the corn yields of major producing countries versus the average monthly temperature of the warmest month of the growing season.

Corn yields

The graph shows a poor correlation of yield to temperature because other factors like technology and precipitation are more important, but there is an insignificant increase in yield with higher temperatures. There is no indication that higher temperatures would lead to reduced crop yields. The corn yield data are here. Corn and other crops are available in a variety of strains that grow best in different climates. Farmers select the strain that grows best in their climate. Some alarmist authors report that higher temperatures would reduce the yields of particular strains, leading to reduced global crop yields. But in reality, farmers would just select another strain of crop in response to a climate change, so there would be no significant impact to global crop yields.

The graph, prepared by Dr. Roy Spencer below shows the increasing world wheat, soybean and corn yields, 1960-2011. It shows the yields (production per area) have been on an upward linear trend for at least 50 years, and show no significant correlation to temperatures. See here.

World Wheat, Soybean, Corn Yield and Temperature


      Warming Effects on Animals

Both higher temperatures and CO2 concentrations enhance plant growth, especially for trees. This increases the habitat available for many animals. The bulk of scientific studies show an increase in biodiversity almost everywhere on Earth that is not restricted by habitat destruction in response to global warming and atmospheric CO2 enrichment.

The global warming alarmist has picked the polar bear as its poster animal. Time magazine has told its readers that they should be worried about polar bear extinction. The data however, does not support reasons for concern. In the Baffin Bay region between North America and Greenland, temperatures have been declining and the polar bear population has declined.  In the Beauford Sea region the temperature has increased and so has the polar bear population. In other areas the polar bear population has been stable. So the trend of polar bear populations relative to temperature have been opposite to what Time would lead its readers to believe.

There has been recent warming in the western arctic as a result of the Pacific Decadal Oscillation, which periodically shifts the climate in the western arctic by changing ocean currents. These cycles have occurred over thousands of years. No evidence exists that suggests that both polar bears and the conservation systems that regulate them will not adapt and respond to the new conditions. Polar bears have persisted through many similar climate cycles. See here for an article by Dr. Mitchell Taylor, Polar Bear Biologist.

Polar bear fossils have been dated to over one hundred thousand years, which means that polar bears have already survived an interglacial period when temperatures were considerably warmer than they are at present and when, quite probably, levels of summertime Arctic sea ice were correspondingly low. 

Canadian scientists summarized the various estimates of polar bear populations at an international meeting in 1965 as follows:
"Scott and others (1959) concluded that about 2,000 to 2,500 polar bears existed near the Alaskan coast. By extrapolation, they arrived at a total polar bear population of 17,000 to 19,000 animals. Vspensky (1961) estimated the world polar bear population at 5,000 to 8,000 animals. Harington (1964) ... believes the world polar bear population is well over 10,000."

In 1993, the Polar Bear Specialist Group press release noted, "The state of knowledge of individual subpopulations ranges from good to almost nothing." Then it said that "the world population of polar bears was thought to be between about 21,000 and 28,000." In 2005 the group reported "The total number of polar bears worldwide is estimated to be 20,000-25,000." In 2013 it was reported that there are now 22,600-32,000 polar bears worldwide, when tallied by nation. See here. The Polar Bear Specialist Group of the International Union for the Conservation of Nature (IUCN) has reported in May 2011 that there was no change in the polar bear population in the most recent four-year period studied. The polar bear population is apparently more than double that of the 1960s.

The graph below was compiled here by Dr. Susan Crockford based on data from the IUCN/SSC Polar Bear Specialist Group.

Dr. Crockford writes, "What is apparent is that the global population of polar bears has not declined over the last 30 years".

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