Global Climate Change: How Do We Know?

Climate Change, Anthropocene, & Associated Issues

NASA indicates that the Earth's climate has changed throughout geologic history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking the beginning of the modern climate era — and of human civilization. Most of these climate changes are attributed to very small variations in Earth’s orbit that change the amount of solar energy our planet receives.

The current warming trend is of particular significance because most of it is extremely likely (greater than 95 percent probability) to be the result of human activity since the mid-20th century and proceeding at a rate that is unprecedented over decades to millennia. Scientific evidence for warming of the climate system is unequivocal. [The the accompanying temperature increase and rate of change are the main concerns, not the absolute CO₂ value becasue high levels of CO₂ were prevalent in deep geologic history.]

This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO₂ has increased rapidly since the Industrial Revolution. (See references: Luthi, D., et al.. 2008; Etheridge, D.M., et al. 2010; Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO₂ record). Find out more about ice cores. Other sources, such as methane and just recently known SF6, also are strong contributors to climate change (more).

Earth-orbiting satellites and other technological advances have enabled scientists to see the big picture, collecting many different types of information about our planet and its climate on a global scale. This body of data, collected over many years, reveals the signals of a changing climate. The heat-trapping nature of carbon dioxide and other gases was demonstrated in the mid-19th century. Their ability to affect the transfer of infrared energy through the atmosphere is the scientific basis of many instruments flown by NASA. There is no question that increased levels of greenhouse gases must cause the Earth to warm in response.

Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that the Earth’s climate responds to changes in greenhouse gas levels. Ancient evidence can also be found in tree rings, ocean sediments, coral reefs, and layers of sedimentary rocks. This ancient, or paleoclimate, evidence reveals that current warming is occurring roughly ten times faster than the average rate of ice-age-recovery warming.

The evidence for rapid climate change is compelling. See the rest of the article and the references in the NASA article.

* Contrary to all of the credible climate scientists, Marechal, current President of the AAPG Division of Environmental Geosciences (DEG), has provided in an editorial in The Explorer, what amounts to a total capitulation of the ethical standards of the profession of geology regarding climate change. Read the short editorial first and then come back to the comments here to see if I am off-base. Marechal Editorial

Marechal claims that the causes of climate change (aka global warming) need to be studied and debated further, when in reality the causes have been studied for 20 years and all credible climate scientists are in agreement. Further, and apparently, Marechal has not bothered to read any of the actual reports on the subject. Further, geologists, especially environmental geoscientists owe a duty to the public to openly support position that impact the general public, not unlike the astronomer has a duty to report to the public on an asteroid or comet on track toward Earth. Further, it does not "best serve society by stepping away from predictions of environmental and climatic cataclysms" The current "brouhaha" is created by those deniers who have ignored and rejected "good scientific analysis and discussion" of the mountain of information available indicating the approaching climate change. We took steps to fix the ozone layer by banning certain aerosols; we can also take steps to minimize global warming.

It is clear to this editor that: 1) our burning of fossil fuels{oil and gas and coal} to produce electricity and to operate cars, trucks, trains, planes, etc), 2) our management of oil and gas production {fugitive emission of methane), 3) our management of livestock {cattle, sheep, etc}, and 4) our manufacture of electrical equipment that produces SF6 (and the fugitive emissions of such from almost all electricity-driven devices) must be stopped or reduced considerably by capturing or eliminating such releases to the atmosphere.

Lastly, and the most unethical, is that Marechal attempts to lull the young geoscientists into complacency by ensuring them that they will "sleep at night with confirmation that the planet will still be habitable when they grow up ...." This is unconscionable and a bare-faced lie. Their children will be the ones who begin to bare the brunt of the changes in climate if nothing is done now! He is attempting to pass the buck to our young geoscientists.

The real question is why do the climate deniers (Marechal and many Republicans) hold such untenable positions?  At the very root is money and fear. Geoscientists holding such positions do not want to rock their personal financial boat (aka do not want to go against the position of the their oil and gas company employers for fear losing their jobs). Some Republicans also fear losing their investments or commitments to the oil and gas companies (also aka having been bought off or leveraged by the oil & gas companies, their financial supporters and associated stakeholders). There is no debate. We have the results of the climate scientists and the deniers wishing to debate these results represent the height of arrogance. Marechal may wish to debate, but he, like other deniers before him, has no credible basis to counter the climate scientists and only offers what amounts to nothing less than BS. Notice how his position contrasts with those of the Geological Society of America (more).

For more information on climate issues, see the I2M Web Portal Search Results: 

Climate Change: http://i2mportal.com/search_resource.php?search_value=Climate+Change&sort=date#page=1

Climate Change Deniers: http://i2mportal.com/search_resource.php?search_value=deniers#page=1

Climate Category: http://i2mportal.com/category.php?sort=name&id=195#page=1