求解一个句子！

半酒凡槽

                                                                                                                                                                                                在曼哈顿语法上面看到的一句话

                                                Citizens of many countries are expressing concern about the environmen-tal damage caused by the widespread release of greenhouse gases,DAM-AGE THAT may be impossible to reverse.


想问一下加粗部分的订正在句子里是做啥成分呢？没有连接词也可以么？


感谢大家～刚开始准备sc有很多不明白的地方
                                       
                               
                       
               

小马过河0066

个人拙见：
同位语的几种情况：
前后都是具体名词，同位语修饰前面的noun
i went to the party with my friend, a teacher from No.1 high school.

前面是具体名词，后面是抽象名词，同位语修饰前面整个句子
I went to the party with my friend, an outing that i would remember for the rest of my life.

前后都是抽象名词，同位语修饰前面的NOUN
the school will hold its annual field day, an outing at which everyone drink beer.

我个人你给的例子是第三种情况，因为“damage”和"(widespread) release (of greenhouse gases)"都是抽象名词
所以damage是修饰"widespread release of greenhouse gases"的同位语
而（that may be impossible to reverse）是一个modifier，限定damage的范围

correct me if i am wrong,thx