文/新浪財經意見領袖專欄作家 金刻羽（哈佛經濟學博士、倫敦政治經濟學院經濟學終身教授）
目前，世界正面臨著類似1930年代經濟蕭條的前景，或許是2009年經濟大衰退的幾倍。對大多數人來說，這可能是我們一生中經歷的最大的經濟事件。這場流行病可與1918年襲擊西班牙的大流感相提並論，那場流感當時感染了西班牙1/4的人口，並且有5000萬人死亡。僅僅在兩個月前，大多數人還認為這場新冠病毒只是一種中國現象，或至多發生在亞洲，就像SARS，我們沒有料想到它會在世界其他國家有爆炸式的傳播。與1918年相比，現代醫學和科技得到了進步，但世界範圍內的聯繫也越來越緊密，每天有1200萬人次通過乘坐飛機在各個國家之間流動。
在目前的情況下，我們面對的不是像2009年的經濟衰退時那樣，美國的產出下降5%，而是美國和全球的產出下降40%的可能性。這一次，不是信貸緊縮導致的銀行體系的癱瘓，消費乏力蔓延到實體經濟。如今，實體經濟的很大一部分完全陷入停滯，這種影響將會進入金融系統，並且重新回來第二次衝擊實體經濟。
在2008年經濟大衰退的高峰時期，美國每個月損失80萬個工作崗位，如今的境況將是每周損失數百萬個工作崗位。政策制定者在美國失業率達到10%時畏縮不前，如今他們在討論的失業率徘徊在30%左右。在典型的經濟衰退中，企業解雇工人是因為社會缺乏消費。如今，企業的做法直接導致大規模失業，因為它們不能也不應該讓人們重返工作崗位。然後，當陷入困境的家庭和企業削減開支時，就會出現第二輪的裁員潮。
我們拿餐飲業舉例，在美國，這是個規模接近一兆美元的行業。還沒有考慮到航空、旅行、娛樂、教育和一些必須面對面的服務。服務業約佔到整體GDP的80%，那麽，我們很容易就能明白，為何40%的產出會一夜蒸發。和2008年最大的區別在於，如今很多基礎面良好的企業也會破產，因為他們沒有生意可做。在2008年金融危機中，美國一些大銀行瀕臨違約，政府當時出手拯救了銀行。如今，政府需要出面拯救一切——包括她的人民、中小企業、銀行和金融機構。
與整個經濟衰退時期相比，全球主要經濟體的政府承諾的一攬子援助規模已經大得多了。美聯儲已經承諾無限購買美國債券，美國財政部通過了美國現代歷史上最大規模的2兆美元經濟刺激計劃。歷史上一貫吝嗇的歐央行已經承諾購買約1兆歐元的歐洲債券。其口號是：竭盡全力。他們聲稱自己正在面臨二戰以來最大的危機！
不過人們很容易理解，儘管貨幣政策反應迅速且規模龐大，但其效果是有限的。原因是這樣的：2007年凍結了支出和信貸，消費者和企業負擔不起重新貸款。因此，旨在降低利率和提供信貸的貨幣政策可以迅速幫助重啟借貸和支出。然而，當由於社會成員產生距離，企業無法持續業務，或是由於隔離措施限制了人們正常工作，那麽貨幣政策就很難使經濟活動恢復正常。
我們是否會面臨經濟蕭條或衰退，要看新冠病毒在全球的傳播會持續多長時間。如果所有國家都能夠采取像中國這樣嚴厲的措施，或者甚至是采取像新加坡、韓國和日本這些國家這樣較為溫和但有效的措施，我都不會如此擔心。但西方國家不像亞洲國家。首先，他們沒有經歷過SARS的經驗，反應遲鈍，很晚才意識到問題的嚴重性。其次，僅僅在幾周的強製隔離，甚至只是要求避免聚集之後，就已經怨聲載道。請注意：這甚至還不是隔離，這只是避免聚集。英國首相鮑裡斯•約翰遜（Boris Johnson）宣布采取隔離措施的幾天后，他父親卻說去酒吧喝酒是一種“必要活動”，有需要的時候他一定會去。我認識的一對住在豪華的鄉村莊園的70多歲高齡的英國夫婦告訴我，如果被要求再隔離一個月，他們會發瘋的。我之前在紐約的同學說，紐約人不可能在家裡待太久，他們寧願感染這種病。而且最有可能發生的事情是——他們受夠了，最終會發展成為群體免疫力。
因此，不僅僅是我們的文化、政治制度、公共設施不同，我們的人民也是不同的。與西方人相比，東亞人是一個更順從的群體，就像與意大利人相比德國人也是這樣。與歐洲人相比，美國人需要的社會娛樂活動更少。上周末巴黎氣象很好，法國人不願錯過離家去海灘的機會。 但是不管是美國人還是歐洲人——他們都厭惡被管制的感覺。他們對技術監視也持懷疑態度，即使危及他們的生命也是如此。
上述的所有意味著不同國家在應對這一流行病時，將采取截然不同的方法。大多數工業化國家采取的是緩解措施，推遲高峰期的到來，而不是采取極端措施去遏製病毒。但這也將意味著他們延誤了工作和經濟的恢復。在中國，我們停止了所有社會活動大約一個月左右，企業正在恢復生機，許多業務已經完全恢復，但西方經濟不會如此。按照他們的策略，經濟恢復少則需要6個月，甚至更久。如果出現二波感染的爆發，則可能需要18個月，或者直到治療方法和疫苗的出現才能恢復正常。如果世界主要經濟體出現12-18個月的經濟停滯，我們將面臨的是比大蕭條更嚴重的挑戰。
因此，我們不能根據中國的抗疫經驗來分析世界經濟的前景。儘管國內已經沒有多少新的確診病例，但社會行為已經發生了根本性的變化。恢復正常工作後，我們仍然需要觀察是否會出現第二波感染，如果沒有，我會對中國的經濟恢復更加樂觀。一旦西方國家的感染率開始下降，股票市場就會恢復正常。到目前為止，6兆美元的股票市值已經蒸發，但最糟糕的時刻還沒有到來。
中國國內的經濟規模足以防止我們的產出出現大幅下降。但是，當我們的經濟恢復正常時，世界其他地區將陷入困境。不僅是出於戰略利益，而且還是道德要求，這都是我們在這個世紀對世界各國施以援手的機會。在國際社會中如此難以建立的信任，將通過我們對人道主義援助真誠而實際的踐行來實現。
附英文原文：
Why are we facing a 1930‘s Economic Depression？
The world is currently facing the prospects of an Economic depression akin to that of the 1930’s， perhaps 10 times the size of the Great recession of 2009． For most of us， it will be the biggest economic event of our lifetime．
The pandemic that has attacked us is comparable to the 1918 Spanish flu， which infected about 1/4 of the population and where 50 million people had died． Only two months ago， most of us believed that the coronavirus will be a Chinese phenomenon， or at most an Asian phenomenon， like SARS． Little did we expect that it will explode in the rest of the world． Compared to 1918， modern medicine and technology has advanced， but we also have vastly greater interconnections around the world， with 12 million people flying each day ．
What we are potentially facing is not a 5% drop in U.S． output， as was the case of the Great Recession in 2009， but a 40% drop in U.S． output and economies around the world． This time around， it is not a paralysis of the banking system where credit is squeezed， and lack of spending spills over to the real economy． Today， it is that a large part of the real economy will be in a complete stall， which will in turn break the financial system， and then come back to affect the real economy a second time round．
During the height of the Great Recession of 2008， the U.S． economy was losing 800，000 jobs per month． Today， it is losing millions of jobs per week． Policymakers balked at a peak of 10 % unemployment rate in the U.S．； today， they are talking about a number that hovers around a 25% unemployment rate． In a typical recession， businesses lay off workers because consumers do not spend enough． Today， businesses destroys employment because they cannot and should not bring people back to work． And then----when distressed families and businesses cut back on spending， there is a second round of layoffs．
Take the restaurant sector alone． In the U.S．， it is a trillion dollar sector． This does not take into account air travel， tourism， entertainment， education， and face to face services． The service sector as a whole is about 80% of GDP． It is easy to see how a 40% evaporation of output can occur in no time． The main difference is that fundamentally sound businesses today may go bankrupt because there is no business． In 2008， a few major banks were on the verge of default． Today， the government has to come out and rescue its people， its businesses large and small， and its banks．
The financial assistance packages that major governments around the world are promising are already on a much larger scale than during the whole of the Great Recession． The Fed has already promised to buy US bonds of `infinity and more’． The Treasury is currently trying to pass a 2 trillion dollar fiscal stimulus， which is the largest fiscal stimulus package in modern U.S． history． The European central bank， which been historically stingy， has pledged to buy about 1 trillion euros worth of European debt． Its motto is ： do whatever it takes． They have claimed that they are facing the biggest crisis since World War II！
But it is easy to understand why monetary policy will be limited in its efficacy despite their rapid response and scale． The reason is that in 2007， it was spending and credit that was frozen． Consumers and businesses cannot afford to replay loans or get new ones． So monetary policy aimed at cutting interest rates and making credit available can help jumpstart borrowing and spending． But when businesses are effectively shut down because of social distancing， because businesses cannot get components， or because quarantines limits people’s ability to work， it is not monetary policy that can jumpstart economic activity．
I would not be so concerned if all countries can take as draco年n measures as our country has taken， or even the more moderate but effective measures that Singapore， Korea and Japan have adopted． But the Western countries are not like Asian countries． First of all， they have not had the experience of SARs， and are slow to react and to recognize the severity of the problem． Second， the people are already complaining of being quarantined after only a few weeks or in many cases a few days of mandatory social distancing． Attention： it is not even quarantine---it is social distancing． Days after the UK prime minister Boris Johnson announced social distancing measures， his father had said suggested that going to a pub may be a `necessity’， and that he would go anyway． My British friends over 70 years old who are staying at luxurious countryside estate have told me that they will go crazy if they are required stay there for one more month． My former classmates in New York said that there is no way that New Yorkers can be kept in their homes for too long． They’d rather get the disease． And---what is most likely going to happen is that they will be fed up， and everyone will end up developing herd immunity．
Thus， it is not only that our culture， political systems， public infrastructure are different． Our people are different． Compared to Westerners， East Asians are a more compliant group． So are the Germans—compared to the Italians． Compared to Europeans， Americans crave and need less socialization． Last weekend saw good weather for Paris， and the Frenchmen could not miss the opportunity to leave their homes for the beach． But from Americans to Europeans--virtually all of them hate perceived notions of suppression． They are also skeptical of technological surveillance even if it is their lives that are at stake．
All of this means that different countries will take very different approaches in fighting the epidemic． Most industrialized countries have taken the approach of mitigation， delaying the peak， rather than radical measures to contain the virus． But that would mean that they delay the resumption of work and the economy． In China， we stopped all activities for about a month or so， and businesses are springing back to life， with much of the operations fully recovered． That would not be the case for Western economies． With their strategy， it will take at least 6 months for the economy to go back to normal， if not longer． If there is a second wave of infections， then it may take 18 months， or whenever a cure and a vaccine is available． If we are facing a 12-18 month halt in economic activities in major economies around the world， we will be facing a challenge even greater than the Great Depression．
Thus， we cannot analyse the prospects of the world economy based on our own experience． Even though there are barely any more new cases arising inside China， social behaviour has fundamentally altered． We will still need to see if a resumption of work can spark off a second wave of infection． If not， I would be more optimistic of China‘s economic recovery． As soon as we see the infection rates starting to decline in Western countries， the stock market will start to come back． So far， 6 trillion dollars of stock market value has already been wiped out and we have yet to see the worst．
The size of our domestic economy is sufficient to prevent a major decline in our output． But the rest of the world will be tanking as we come back to life． It is an opportunity of the century for us to help the rest of the world， not only out of strategic interests， but also out of a moral imperative． The trust that has been so difficult to build in the international community will come about through our genuine and practical efforts of humanitarian assistance．
(本文作者介紹：哈佛經濟學博士、倫敦政治經濟學院經濟學終身教授)
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