寻找细节耕地流失的“历史汇率”——地球科学堆栈交换江南电子竞技平台江南体育网页版 最近30从www.hoelymoley.com 2023 - 07 - 10 - t15:20:06z //www.hoelymoley.com/feeds/question/6611 https://creativecommons.org/licenses/by-sa/4.0/rdf //www.hoelymoley.com/q/6611 8 寻找细节的“历史汇率”耕地损失 O.M.Y. //www.hoelymoley.com/users/3267 2015 - 09 - 28 - t12:50:36z 2016 - 12 - 18 - t21:14:32z < p >在做研究的问题< em > < / em >沙漠化土地退化(又名< em > < / em >)我一直运行在相同的基本句子但是没有源或细节来支持或澄清:< / p > < blockquote > < p >“耕地损失估计有30到35次历史汇率。”< / p > < /引用> < p >谁能帮我找到一个指定的源这个“历史汇率”?在历史上被测量的时间长度是什么?这些数据的地理范围是什么?< / p >

Failing a specific source for this quote, can anyone provide a reliable source for the data subject the quote refers to (i.e. a long term track record of desertification)?

//www.hoelymoley.com/questions/6611/-/6627 # 6627 2 答案由戈登斯坦格寻求细节耕地流失的“历史汇率” 戈登斯坦格 //www.hoelymoley.com/users/4507 2015 - 10 - 01 - t10:38:35z 2015 - 10 - 01 - t10:38:35z < p >没有上下文,但是表面上这是一个没有意义的报价。全球有一个净< em > < / em >增加耕地面积大约8000年前从接近于零,当前最大的就在地球的生物生产力总值的40%。“耕地损失”可以指土地失去了城市化、盐渍化、沙漠化。也可能使一个区别对农业土地失去了水文干预,减少流动的阿姆河,和苏尔Darya在中亚。此外,在未来几十年里我们将开始看到农业土地失去了对气候变化的影响。没有单一的评估耕地流失的历史汇率是有意义的。一个单独评估的各种流程,然后总在地区层面上。< / p > //www.hoelymoley.com/questions/6611/-/6683 # 6683 2 答案为寻找细节userLTK耕地流失的“历史汇率” userLTK //www.hoelymoley.com/users/2717 2015 - 10 - 10 - t11:56:04z 2015 - 10 - 12 - t05:06:01z < p >这是一个奇怪的问题。< / p >

I agree with Gordon Stranger, without context, (and a mention of some link to peer reviewed research, or at least, some kind of measurement), it's pretty meaningless.

I did a a google search and checked links with books.google.com in them to search for a source but everything refers back to UNCCD and UNCCD, as far as I read their reports, never explains or provides a source for that sentence.

Google Search for books

List of reports I went through a few - no luck.

I did find this:

enter image description here

Source: but the problem is, they're using a different criteria than you. Forest can be cleared to create new arable land, so that's why they show an increase when UNCCD shows a decrease. If you combine this chart with deforestation, you might have something a little bit close to what you're looking for.

In the US, (edit) farm land (not necessarily arable land) has decreased but food production has increased due to improved technology, fertilizer and all that good stuff.

Chart

Source

Bad farming methods leads to loss of arable land much faster than good methods. Here's a good answer on the dustbowl that you might find interesting and even early societies, thousands of years ago, they lost arable land cause there were processes that happened that they didn't understand, explained more here.

Environmental effects, mostly tend to be cyclical and are probably harder to measure outside of human effects. California might have a big drought one year and have a great growing season the next. The droughts we experience don't make the land permanently not arable, just for 1 growing season. Floods - might have a bigger effect if they wash away good land but they can also have the opposite effect, depositing rich silts adding nutrients to the soil. Over long term, climate change can affect arable land, for example, 13,000 years ago / give or take, the Sahara was a rich forest with huge lakes (We know this by fossils that remain there) and that may be a cycle that comes and goes with every orbital tilt of the Earth. During the last ice age, much land was covered by ice, but lower sea levels left lots of rich valleys that are now covered by water. The story of Noah and Gilgamesh are thought to be based on the flooding of one such fertile valley, caused in part by the end of the ice age and rising water.

So, at least from an environmental perspective, it's a complicated question with lots of moving parts. Hope that helps, though I'm not sure it does. I was curious about what you asked so I looked into it a bit.

//www.hoelymoley.com/questions/6611/-/6704 # 6704 2 答案为寻找细节Eubie画“历史汇率”的耕地损失 Eubie画 //www.hoelymoley.com/users/4487 2015 - 10 - 12 - t06:24:27z 2015 - 11 - 01 - t19:59:22z < p > <强> < em >编辑——< a href = " http://www.grida.no/publications/other/geo2000/ " rel =“nofollow”>发现完整的报告…在挪威。< / > < / em > < /强> < / p > <人力资源> < p >引用你试图源是一个经常重复(1999 - 2002)话题,克劳斯特普费尔(托普夫),联合国环境规划署的负责人。< a href = " http://www.grida.no/news/default/1961.aspx " rel =“nofollow”>我能找到最古老的实例在伦敦,1999年。< / > < / p > < blockquote > < p >耕地正在消失的速度增长,目前历史汇率的30至35倍。只有一个半亿公顷是最初的三个半美元。潜在生产力的损失由于土壤侵蚀全球估计相当于每年大约2000万吨的谷物或占全球总产量的1%。< / p >

Other later versions of his quote form a larger paragraph with one or two preceding sentences about soil loss in Africa, so the scope may not in fact be global. He and several others sometimes credit the UNEP Global Environment Outlook 2000 (GEO-2000) report, then link to this overview. I have electronically combed through the above overview and found nothing and I can not find a full report online. There are many alleged links, but they all go to the overview. FOUND IT HERE.

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