????不幸的是，這并不是經濟學家們第一次警告全球范圍內的房價泡沫。比方說，加拿大房價上漲已經讓當地官員們擔憂了好幾年。問題是，在資產泡沫積累的過程當中，很難找到辦法解決。監管機構可以努力確保信貸不過于寬松，同時收緊借貸標準，但有些時候，泡沫趨勢可以壓倒這些措施。消除泡沫唯一可靠的方式就是讓它破裂，但這個辦法可能給那些經濟不那么好的國家帶來嚴重的后果。

????或許，一個更值得探討、同時也有助于政策制定者避開未來房地產泡沫的問題是，為什么房地產領域目前存在這么多正在發酵的泡沫？或許，我們可以參照一下經濟學家托馬斯?皮凱蒂的暢銷書《21世紀資本論》（Capital in the 21st Century）所引發的爭論。

????皮凱蒂的這本書宣稱，不斷擴大的收入不平等是資本主義體系的核心特點，因為資本回報率總是高于經濟增長率。結果是，資本變得更加有價值，而較低的經濟增速不足以讓那些不擁有資本（比如房地產或金融資產）的人變得更加富有。最近幾周，皮凱蒂論點的批評人士指出，他的論據有瑕疵，因為過去20年資本價值的增長大部分來自全球范圍內的房地產價值增長。如果正如以上分析所指出的那也難怪，房地產被高估，那么，皮凱蒂宣稱的資本回報正在增長可能就是假象。

????但如果房地產沒有被高估呢？如果經濟發生了一些變化，造成房地產升值呢？越來越多的研究正是這么認為的：隨著發達國家經濟對農業和制造業的依賴程度降低，對于依托寶貴創意、緊密合作的創新行業的依賴程度上升，土地再一次變得非常重要。

????我們可以，這一幕正在美國上演：舊金山、哥倫比亞特區、紐約和其他創新城市的房租正在隨同工資一起高漲。在大多數高產勞動者看到房地產價值上漲的環境中，人們想買房、而不是租房不無道理。那么，什么力量會阻止這個價格上漲的趨勢呢？

????有這樣的解釋，大家有理由相信，最近發達國家房地產價格上漲既有理性因素（經濟發展使得位置變得更為重要），也有非理性因素（人們認為沒有什么能阻止本輪上漲行情）。很難說哪一個力量是推高房地產價格的更大因素，但價格過去怎么樣并不意味著它未來就會繼續這樣。

????換句話說，或許我們認為的泡沫實際上就是房地產市場在告訴我們，決策層需要在經濟最具活力的地區增加住房供應。（財富中文網）

????Unfortunately, this isn’t the first time that economists have warned of housing bubbles around the world. Price increases in Canada have had officials worried for years, for instance. The problem is, it’s difficult to do anything about a growing asset bubble while it’s in progress. Regulators can work to make sure that credit isn’t too widely available and lending standards are tightened, but sometimes the logic of a bubble can overcome even these measures. The only reliable way to eliminate a bubble is to let it burst, which could lead to terrible consequences for the country’s economies in question.

????Perhaps a more interesting question, and one that could help policy makers avoid these real estate bubbles in the future, is why are there so many bubbles growing in this particular asset right now? For that it is useful to turn to the recent debate over economist Thomas Piketty’s best-selling Capital in the 21st Century.

????Piketty’s book alleges that growing income inequality is a central feature of capitalist systems, because the returns to capital will almost always be higher then economic growth. The result is that capital becomes ever more valuable, while there is not enough economic growth to make richer those who don’t own capital (like real estate or financial assets). Critics of economist Thomas Piketty’s thesis have argued in recent weeks that his argument is flawed because most of the run up in value of capital in the past 20 years is due to the run up in the value of real estate around the world. If real estate is overvalued, as the analysis above suggests, then Piketty’s claim that the return on capital is growing could be an illusion.

????But what if real estate isn’t overvalued? What if there is something happening in the economy that’s causing real estate to become more valuable? A growing body of research is arguing just that: As developed economies become less reliant on agriculture and manufacturing, and more reliant on creative industries that thrive on close collaboration for a generation of valuable ideas, land is becoming once again very important.

????We can see this happening in the U.S., where rents in cities like San Francisco, Washington D.C., New York and other innovative cities are skyrocketing along with salaries. In an environment where the most productive workers are seeing rapidly rising property values, it makes sense that people would want to buy a home rather than rent. After all, what force is going to stop this trend in rising prices?

????With this explanation, you have reason to believe that the recent run up in real estate prices in developed countries has both a rational component (the evolution of the economy is making location more important) and an irrational component (people think that nothing will stop this trend). It’s difficult to say which force could be a bigger factor pushing real estate prices higher, but it’s important to realize that just because prices have always behaved a certain way in the past doesn’t mean it will continue that way in the future.

????In other words, perhaps what we think is a bubble is really just the real estate market telling us that policy makers need to do more to allow more housing supply to be built where economies are most dynamic.