Disturbing losses of protective ozone near Earths equator may be tied to

first_img Email Disturbing losses of protective ozone near Earth’s equator may be tied to short-lived chemicals NASA Goddard Sign up for our daily newsletter Get more great content like this delivered right to you! Country Country * Afghanistan Aland Islands Albania Algeria Andorra Angola Anguilla Antarctica Antigua and Barbuda Argentina Armenia Aruba Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia, Plurinational State of Bonaire, Sint Eustatius and Saba Bosnia and Herzegovina Botswana Bouvet Island Brazil British Indian Ocean Territory Brunei Darussalam Bulgaria Burkina Faso Burundi Cambodia Cameroon Canada Cape Verde Cayman Islands Central African Republic Chad Chile China Christmas Island Cocos (Keeling) Islands Colombia Comoros Congo Congo, the Democratic Republic of the Cook Islands Costa Rica Cote d’Ivoire Croatia Cuba Curaçao Cyprus Czech Republic Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Falkland Islands (Malvinas) Faroe Islands Fiji Finland France French Guiana French Polynesia French Southern Territories Gabon Gambia Georgia Germany Ghana Gibraltar Greece Greenland Grenada Guadeloupe Guatemala Guernsey Guinea Guinea-Bissau Guyana Haiti Heard Island and McDonald Islands Holy See (Vatican City State) Honduras Hungary Iceland India Indonesia Iran, Islamic Republic of Iraq Ireland Isle of Man Israel Italy Jamaica Japan Jersey Jordan Kazakhstan Kenya Kiribati Korea, Democratic People’s Republic of Korea, Republic of Kuwait Kyrgyzstan Lao People’s Democratic Republic Latvia Lebanon Lesotho Liberia Libyan Arab Jamahiriya Liechtenstein Lithuania Luxembourg Macao Macedonia, the former Yugoslav Republic of Madagascar Malawi Malaysia Maldives Mali Malta Martinique Mauritania Mauritius Mayotte Mexico Moldova, Republic of Monaco Mongolia Montenegro Montserrat Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Caledonia New Zealand Nicaragua Niger Nigeria Niue Norfolk Island Norway Oman Pakistan Palestine Panama Papua New Guinea Paraguay Peru Philippines Pitcairn Poland Portugal Qatar Reunion Romania Russian Federation Rwanda Saint Barthélemy Saint Helena, Ascension and Tristan da Cunha Saint Kitts and Nevis Saint Lucia Saint Martin (French part) Saint Pierre and Miquelon Saint Vincent and the Grenadines Samoa San Marino Sao Tome and Principe Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Sint Maarten (Dutch part) Slovakia Slovenia Solomon Islands Somalia South Africa South Georgia and the South Sandwich Islands South Sudan Spain Sri Lanka Sudan Suriname Svalbard and Jan Mayen Swaziland Sweden Switzerland Syrian Arab Republic Taiwan Tajikistan Tanzania, United Republic of Thailand Timor-Leste Togo Tokelau Tonga Trinidad and Tobago Tunisia Turkey Turkmenistan Turks and Caicos Islands Tuvalu Uganda Ukraine United Arab Emirates United Kingdom United States Uruguay Uzbekistan Vanuatu Venezuela, Bolivarian Republic of Vietnam Virgin Islands, British Wallis and Futuna Western Sahara Yemen Zambia Zimbabwe Click to view the privacy policy. Required fields are indicated by an asterisk (*)center_img Thirty years after nations banded together to phase out chemicals that destroy stratospheric ozone, the gaping hole in Earth’s ultraviolet (UV) radiation shield above Antarctica is shrinking. But new findings suggest that at midlatitudes, where most people live, the ozone layer in the lower stratosphere is growing more tenuous—for reasons that scientists are struggling to fathom.“I don’t want people to panic or get overly worried,” says William Ball, an atmospheric physicist at the Physikalisch-Meteorologisches Observatorium Davos World Radiation Centre in Switzerland. “But there is something happening in the lower stratosphere that’s important to understand.”Several recent studies, including one published last month in Geophysical Research Letters, point to a robust recovery of stratospheric ozone concentrations over Antarctica—the long-awaited payoff after the Montreal Protocol in 1987 mandated a global phaseout of chlorofluorocarbons and other ozone-eating compounds. An unheralded group of chemicals may complicate the current view of ozone-depleting substances in the midlatitudes. By April ReeseFeb. 6, 2018 , 12:00 AM But recent evidence indicates that the global campaign to mend the ozone layer is far from over. In an analysis published today in Atmospheric Chemistry and Physics, Ball and colleagues combined satellite data to examine ozone at midlatitudes, from Earth’s surface on up through the troposphere and the stratosphere. They found that from 1998 to 2016, ozone in the lower stratosphere ebbed by 2.2 Dobson units—a measure of ozone thickness—even as concentrations in the upper stratosphere rose by about 0.8 Dobson units. “We saw it at almost every latitude and every altitude below about 25 kilometers,” Ball says. “That made us very concerned that perhaps this was something very real that no one looked at before.”The ozone layer’s total thickness—not just concentrations in the upper stratosphere—is vital for absorbing UV light. “What matters most for UV at Earth’s surface is the total column amount of ozone overhead,” says co-author Sean Davis, a research scientist with NOAA’s Earth System Research Laboratory in Boulder, Colorado. Although previous studies had suggested a decline in lower stratospheric ozone, no one had combined satellite data to look at what was happening across such a wide swath of the globe and so far down in the ozone layer.Ball and his colleagues suspect that the culprit is “very short-lived substances” (VSLSs): ozone-eating chemicals such as dichloromethane that break down within 6 months after escaping into the atmosphere. Researchers had long assumed that VSLSs’ short lifetime would keep them from reaching the stratosphere, but a 2015 Nature Geoscience study suggested that the substances may account for as much as 25% of the lower stratosphere’s ozone losses. Whereas many VSLSs are of natural origin—marine organisms produce dibromomethane, for example—use of humanmade dichloromethane, an ingredient in solvents and paint removers, has doubled in recent years. “We should study [VSLSs] more completely,” says Richard Rood, an atmospheric scientist at the University of Michigan in Ann Arbor. But because the compounds are released in small quantities, he says, “They’re going to be difficult to measure.”Climate change may also be a factor, for example by sweeping ozone out of the tropics, the study suggests. It’s vital to determine what’s eating away at ozone in the midlatitudes, where the majority of the world’s population resides. “The potential for harm in lower latitudes may actually be worse than at the poles,” says Joanna Haigh, co-director of the Grantham Institute at Imperial College London. “The decreases in ozone are less than we saw at the poles before the Montreal Protocol was enacted, but UV radiation is more intense in these regions.”Ball and others emphasize that the Montreal Protocol has still been a success. “I don’t think it in any way says there’s something fundamentally wrong with how we’ve been dealing with the ozone problem,” says Rood, referring to the study. “What it says to me is that we’re now looking at effects that are more subtle than that original problem we were taking on” when the Montreal Protocol was adopted.last_img

Leave a Reply

Your email address will not be published. Required fields are marked *