【纽伦港新动态•第342期】低增长环境下的货币政策
文/ Benoît Cœuré（欧洲央行执行委员会成员）；编译/邵杨楠
自危机爆发以来，欧洲央行采取了各种非常规措施以满足其通货膨胀目标，包括负存款准备金率，有针对性的长期再融资操作和资产购买。 这些措施仍然是必要的，并且是有效的。 但在公开辩论中，越来越关注这些措施的潜在负面影响及其部署的理由。 这引发了两个问题：为什么我们首先启动非常规货币政策？我们如何减少货币政策在中期内的负面溢出风险？
Since the onset of the crisis, the ECB has introduced a wide range of unconventional measures in order to meet its inflation objective, including negative deposit facility rates, targeted long term refinancing operations, and asset purchases. These measures were – and remain – necessary, and have been effective. But in the public debate, there is an increasing focus on the potential negative side effects of these measures and the rationale behind their deployment. This triggers two questions: why did we launch unconventional monetary policy in the first place? And how can we mitigate the potential risk of negative spillovers from monetary policy over the medium term?
第一个问题的答案是明确的——这些措施已经对全球金融危机造成的巨大负面冲击作出反应，这加剧了一些结构性因素，甚至在危机之前推迟了实际利率。非常规措施是对低全球利率的挑战的反应，而不是其原因。
The answer to the first question is clear – these measures have been taken to react to the large negative shock caused by the global financial crisis, which has exacerbated a number of structural factors that have been driving down real interest rates even before the crisis. The unconventional measures are a reaction to the challenge of low global interest rates, not their cause.
在今天的发言中，我将阐述由低利率和低生产率增长等结构性因素引起的货币政策挑战。 了解这些挑战的结构性质是回答我关于减轻未来货币政策潜在溢出风险的第二个问题的关键。
In my remarks today I will set out the challenges for monetary policy caused by structural factors such as low interest rates and low productivity growth. Understanding the structural nature of these challenges is key to answering my second question on mitigating potential spillover risks from monetary policy in the future.
低生产率增长对货币政策的影响
The impact of low productivity growth on monetary policy
要理解货币政策的结构性挑战，考虑设定货币政策的两个相互关联的概念——潜在产出和均衡利率是有用的。了解这两个概念之间的相互作用是欧洲中央银行目前政策背景的核心。 它们如何演变将决定通货膨胀的未来路径，以及在什么阶段货币政策最终将正常化。
To understand the structural challenges for monetary policy, it is useful to consider two interlinked concepts for the setting of monetary policy – potential output and equilibrium interest rates. Understanding the interplay between these two concepts is at the heart of the current policy settings of the European Central Bank. How they evolve will determine the future path for inflation and at what stage monetary policy can eventually be normalised.
潜在产出表示可持续利用资本和劳动力的活动水平。平衡名义利率是指名义利率的水平，其中活动没有上升或下降压力，由两部分组成：实际平衡率和通货膨胀预期。高于潜在水平的实际活动水平对通货膨胀造成上升压力，低于潜在水平造成下降压力。以类似的方式，将实际利率设定在平衡利率以下刺激经济活动，而将利率设定在平衡之上限制了活动。
Potential output represents the level of activity where capital and labour are sustainably used. Equilibrium nominal rates are the level of nominal interest rates where there is neither upward nor downward pressure on activity, and are composed of two parts: the real equilibrium rate and inflation expectations. Actual levels of activity above potential put upward pressure on inflation and levels below potential put downward pressure. In similar fashion, setting actual interest rates below equilibrium rates stimulates economic activity, whereas setting interest rates above equilibrium restrains activity.
近年来，欧元区的经济活动一直低于潜力——换句话说，产出缺口是负的——这给通货膨胀带来了下行压力。经典教科书的处方很简单：放松货币政策，推动利率低于均衡，刺激产出，恢复潜力，并产生通货膨胀压力，实现通货膨胀目标。一般来说，欧洲央行自危机以来的货币政策符合教科书处方。
Over recent years, economic activity in the euro area has been below potential – in other words there has been a negative output gap – which has put downward pressure on inflation. The classic textbook prescription is simple: loosen monetary policy to drive interest rates below equilibrium, stimulating output to bring it back to potential and generate inflationary pressures to achieve the inflation objective. In general terms, the ECB’s monetary policy since the crisis fits that textbook prescription.
但细节也很重要。教科书中的简单模型假设潜在产出的增长和均衡利率的速率是固定的和不变的。实际上，欧元区和其他发达经济体的生产率增长放缓。加上不利的人口结构，生产率的放缓降低了潜在产出增长和均衡利率。生产率的下降在欧元区尤其明显，因为欧元区的全要素生产率和每个就业人口的资本都明显放缓。
But the finer details also matter. Simple models in textbooks assume that the growth of potential output and the rate of equilibrium interest rates are fixed and immutable. In reality, productivity growth has slowed in the euro area and other advanced economies. Combined with unfavourable demographics, the slowdown in productivity has depressed potential output growth and lowered equilibrium interest rates. The productivity slowdown has been particularly pronounced in the euro area, where both total factor productivity and capital per employed person have markedly slowed down.
这些变化对于货币政策的行为是重要的，它们造成了一个困境。增长低于潜力的增长增加了对宏观经济稳定的需要。与此同时，公共和私人债务的过剩以及它们通过银行——主权关系的相互作用削弱了财政政策的使用，给货币政策带来了更大的负担，以实现稳定。然而，均衡利率的下降减少了传统货币政策工具刺激经济的运作利润率。
These changes matter for the conduct of monetary policy, and they create a dilemma. The slowdown in growth below potential has increased the need for macroeconomic stabilisation. At the same time, the overhang of public and private debt and their interaction through the bank-sovereign nexus impairs the use of fiscal policy and places a greater burden on monetary policy to carry out that stabilisation. Yet the fall in equilibrium rates reduces the margin of operation for traditional monetary policy instruments to stimulate the economy.
货币政策面临的压力增加
The increased burden on monetary policy
总而言之，长期低于潜在的增长需要强有力的政策行动，以防止低增长成为长期的根深蒂固。 但与此同时，潜在增长的下降也增加了货币政策对实行宏观经济稳定的负担。
Taken together, a long period of growth below potential requires robust policy action to prevent the low growth from becoming entrenched into the long run. But at the same time, falling potential growth also increases the burden on monetary policy to carry out that macroeconomic stabilisation.
鉴于19个国家政府财政政策的分散性质以及欧洲财政规则在创造激励措施以建立国家财政空间方面的成功有限，欧元区的政策组合已经严重倾向于货币政策。大多数欧元区国家的可用财政空间另外受到从危机中继承的公共债务的支配。较低的潜在增长和较弱的通货膨胀抑制了公共债务比率的减少，通过作用于分数的两侧。由于较高的结构性失业和较低的通货膨胀造成的较低的税收收入带来的较高支出限制了政府节省，即减少分子的能力。低通货膨胀增加了服务于一定水平的名义债务所需的实际储蓄。类似地，较弱的潜在生长降低了增加分母和从突出端生长的能力。自危机以来，公共债务的过剩不仅降低了财政政策分担货币政策的宏观经济稳定负担的能力，而且也削弱了通过主权 - 银行关系的货币政策传递。
The policy mix in the euro area is already heavily tilted towards monetary policy given the decentralised nature of fiscal policy by 19 national governments and the limited success of European fiscal rules in creating incentives to build up national fiscal space. The available fiscal space in most euro area countries is in addition constrained by the overhang of public debt inherited from the crisis. Lower potential growth and weaker inflation inhibit the reduction of public debt ratios by acting on both sides of the fraction. Higher expenditure arising from higher structural unemployment and lower tax revenues from weaker inflation restrict the ability of governments to save, i.e. reduce the numerator. And low inflation increases the real savings required to serve a given level of nominal debt. Similarly, weaker potential growth lessens the ability to increase the denominator and grow out of the overhang.
Since the crisis, the overhang of public debt has not just reduced the ability of fiscal policy to share the burden of macroeconomic stabilisation with monetary policy, but it has also impaired the transmission of monetary policy through the sovereign-bank nexus.
欧洲央行最近的研究表明，在主权危机期间，强调国家的银行增加了对国内主权国家的持有。 这对于公共银行和最近被拯救的银行尤其明显。由于强调主权债券的价格下跌，这些银行被迫去杠杆化，减少其贷款。这种贷款下降不仅局限于国内市场——总部在强调国家的银行的外国子公司也减少了贷款。国内银行主权债券购买作为一种有效的稳定机制面临财政压力的概念，因此需要资格。
Recent research by the ECB shows that during the sovereign crisis, banks in stressed countries increased their holdings of domestic sovereigns.This was particularly marked for publicly owned banks and recently bailed-out banks. As the price of stressed sovereign bonds fell, these banks were forced to deleverage, reducing their lending. This drop in lending was not just confined to the domestic market – foreign subsidiaries of banks with head offices in stressed countries also reduced lending. The notion that sovereign bond purchases by domestic banks acts as a useful stabilising mechanism in the face of financial stress therefore needs qualification.
货币政策可操作空间减小
The reduced margin of operation for monetary policy
正如我刚才提到的，下降的增长率增加了对宏观经济稳定的需要，并对货币政策施加更大的负担以实现稳定。但它也影响了货币政策刺激经济的能力。这是因为产出的长期增长是均衡利率的一个重要决定因素，在过去三十年的大部分时间里，它在主要发达经济体中一直在下降。
As I have just mentioned, falling growth rates had increased the need for macroeconomic stabilisation, and put greater burden on monetary policy to carry out that stabilisation. But it has also affected the capacity of monetary policy to stimulate the economy. That is because the long-run growth in output is an important determining factor of equilibrium interest rates, which have been falling in major advanced economies for the best part of the past three decades.
如上所述，为了在经济中产生通货膨胀压力，中央银行必须将利率设定在低于均衡水平。 由于均衡利率下降，利率也是刺激性的。估计均衡率是棘手的，估计值受到不确定性带的影响。 但一系列估计将欧元区的实际均衡利率，也就是说均衡利率减去通货膨胀预期，接近零，一些措施甚至是负数。
As I noted above, in order to generate inflationary pressure in the economy, central banks have to set interest rates below equilibrium. As equilibrium interest rates have declined, so has the interest rate that is stimulatory. Estimating equilibrium rates is tricky, and estimates are subject to bands of uncertainty. But a range of estimates puts the euro area real equilibrium rate, which is to say the equilibrium rate minus inflation expectations, at close to zero, with some measures even negative.
为了提供所需的适应性货币政策以使通货膨胀回到我们的目标，欧洲央行需要使主要再融资率为零，我们的存款利率自2014年以来一直为负。这些低和负利率是均衡利率下降的直接后果。 如果这个比率更高，我们的利率设置也会一样。如果不能跟随均衡利率走低，将会造成被困在低增长，低通货膨胀平衡或甚至陷入通货紧缩螺旋的风险中。
To provide the required monetary accommodation to bring inflation back to our objective, the ECB has needed to bring the main refinancing rate to zero, and our deposit facility rate has been negative since 2014. These low and negative rates are a direct consequence of the decline in the equilibrium rate. If that rate were higher, so would our interest rate settings. Failing to follow the move lower in the equilibrium rate would have created the risk of remaining trapped in a low growth, low inflation equilibrium or even of falling in a deflationary spiral.
但是，低利率的走势还是有限的。首先是物理下限，家庭和企业将持有现金。其他中央银行的经验表明，物理下限低于我们目前存款准备率的水平。但是，很可能存在经济下限，通过银行的货币政策传输的负面影响超过低利率对经济活动的积极好处。低利率对短期和长期的银行盈利能力都有影响，可能会影响到信贷准备和金融稳定性。
But there are limits to how low interest rates can go. First of all there is the physical lower bound, where households and businesses disintermediate the banking sector and hold their money in cash. Experience of other central banks shows that the physical lower bound is below where we currently have our deposit facility rate. But there may well exist an economic lower bound at which the negative impact on monetary policy transmission through banks outweighs the positive benefits of low rates for economic activity. Low interest rates have implications for bank profitability in both the short and long term and can weigh on credit provision and financial stability.
这种负面影响到目前为止还没有实现，部分原因是较低利率最初在银行的固定收益投资组合上产生了资本收益，并降低了银行的融资成本，部分原因是低利率对银行的数量和风险的整体积极影响贷款。但随着时间的推移，下跌的利率将挤压银行利息空间。
Such negative effects have not materialised so far, partly because lower rates have initially generated capital gains on banks’ fixed-income portfolios and lowered banks’ funding costs, and partly thanks to the overall positive impact of low rates on the volume and riskiness of bank loans. But over time, falling rates will squeeze bank interest margins.
从长远来看，如果低利率导致资产价格泡沫，一旦利率上升，这些资产价格泡沫容易出现急剧逆转，因此也存在金融稳定的风险。同样，如果银行通过增加对低质量借款人的贷款来“寻找收益”，或者如果他们向非盈利公司滚动非盈利的“僵尸”贷款，则可能有更高的总违约风险。
In the longer run, there are also risks to financial stability if low interest rates result in asset price bubbles, which are vulnerable to sharp reverses once interest rates rise. Similarly, if banks “search for yield” by increasing lending to lower quality borrowers or if they roll over non profitable, “zombie” loans to ailing companies, there may well be a higher aggregate default risk.
欧洲央行工作人员的估计表明，相对于没有采取政策行动的情况，欧元区最近的货币政策行动迄今为止对银行盈利能力是净正的，我们没有看到今天的资产价格泡沫将威胁欧元区的金融稳定。但如果利率太低，负面影响可能会占主导地位，并削弱我们措施的有效性。
ECB staff estimates suggest that recent monetary policy actions in the euro area have so far been net positive for bank profitability, relative to a scenario of no policy action, and we don’t see today asset price bubbles which would threaten the euro area’s financial stability. But if rates are low for too long, the negative effects may well dominate and impair the effectiveness of our measures.
当然，低利率并不是影响欧元区银行盈利能力的唯一因素。欧洲作为一个整体是超额的银行，多个管辖区已经受益于低利润率和高成本收入比几年。由于在可预见的未来利率可能保持低位，即使货币政策正常化，银行也必须重新审视其业务模式，以确保中期持续的盈利能力。
Of course, low interest rates are not the only factor affecting bank profitability in the euro area. Europe as a whole is overbanked, and a number of jurisdictions have suffered from low profitability and high cost-to-income ratios for several years. With interest rates likely to remain low for the foreseeable future, even once monetary policy normalises, banks will have to revisit their business models to ensure continued profitability over the medium term.（完）
文章来源：欧洲央行官网2016年10月28日（原文有删减，本文仅代表作者观点）
本篇编辑：邵杨楠
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